Purged packages, now APT says many packages (half the system) are no longer required

Question

Purged unused Modem + Printer + Bluetooth drivers, now APT says 'half the system is no longer required'

However removing them will break my os. What do you do to fix this? How do I re-install the packages these are allegedly depended upon?

2048-qt alsa-base appstream apt-config-icons apt-config-icons-hidpi apt-config-icons-large apt-config-icons-large-hidpi apt-xapian-index arc-theme avahi-utils bolt breeze-cursor-theme compton compton-conf compton-conf-l10n cups-pk-helper dc debconf-kde-data dns-root-data dnsmasq-base efibootmgr fcitx fcitx-bin fcitx-config-common fcitx-config-gtk fcitx-data fcitx-frontend-all fcitx-frontend-gtk2 fcitx-frontend-gtk3 fcitx-frontend-qt4 fcitx-frontend-qt5 fcitx-module-dbus fcitx-module-kimpanel fcitx-module-lua fcitx-module-x11 fcitx-modules fcitx-ui-classic fcitx-ui-qimpanel fcitx5-module-quickphrase-editor fonts-freefont-ttf fonts-kacst fonts-kacst-one fonts-khmeros-core fonts-lao fonts-lklug-sinhala fonts-noto-cjk fonts-sil-abyssinica fonts-sil-padauk fonts-symbola fonts-thai-tlwg fonts-tibetan-machine fonts-tlwg-garuda fonts-tlwg-garuda-ttf fonts-tlwg-kinnari fonts-tlwg-kinnari-ttf fonts-tlwg-laksaman fonts-tlwg-laksaman-ttf fonts-tlwg-loma fonts-tlwg-loma-ttf fonts-tlwg-mono fonts-tlwg-mono-ttf fonts-tlwg-norasi fonts-tlwg-norasi-ttf fonts-tlwg-purisa fonts-tlwg-purisa-ttf fonts-tlwg-sawasdee fonts-tlwg-sawasdee-ttf fonts-tlwg-typewriter fonts-tlwg-typewriter-ttf fonts-tlwg-typist fonts-tlwg-typist-ttf fonts-tlwg-typo fonts-tlwg-typo-ttf fonts-tlwg-umpush fonts-tlwg-umpush-ttf fonts-tlwg-waree fonts-tlwg-waree-ttf fwupd fwupd-signed fwupdate gir1.2-nm-1.0 gir1.2-notify-0.7 gir1.2-packagekitglib-1.0 gir1.2-polkit-1.0 gir1.2-secret-1 gir1.2-udisks-2.0 gnome-accessibility-themes gnome-themes-extra gnome-themes-extra-data gtk2-engines-murrine gtk2-engines-pixbuf haveged hplip-data htop iio-sensor-proxy inputattach kactivities-bin kactivitymanagerd kcalc kde-cli-tools kde-cli-tools-data kde-style-breeze kerneloops laptop-detect libappstream-glib8 libappstream4 libappstreamqt2 libcdr-0.1-1 libcolamd2 libconfig9 libdebconf-kde1 libdrm-dev libefiboot1 libegl1-mesa-dev libfcitx-config4 libfcitx-core0 libfcitx-gclient1 libfcitx-qt5-1 libfcitx-qt5-data libfcitx-utils0 libfreehand-0.1-1 libfwup1 libfwupd2 libgcab-1.0-0 libgettextpo0 libgl1-mesa-dev libgles1 libgles2-mesa-dev libglib2.0-dev libglib2.0-dev-bin libglu1-mesa-dev libglvnd-core-dev libglvnd-dev libhavege1 libhpmud0 libkf5activities5 libkf5bluezqt-data libkf5bluezqt6 libkf5calendarevents5 libkf5networkmanagerqt-dev libkf5networkmanagerqt-doc libkf5networkmanagerqt6 libkf5plasma5 libkf5plasmaquick5 libkf5sane-data libkf5sane5 libkf5style5 libkf5su-bin libkf5su-data libkf5su5 libkworkspace5-5 libmbim-glib4 libmbim-proxy libmimetic0v5 libminiupnpc17 libminizip1 libmspub-0.1-1 libmysqlclient20 libnatpmp1 libndp0 libnm-dev libnm0 libopengl0 libpackagekit-glib2-18 libpackagekitqt5-1 libpagemaker-0.0-0 libpcre16-3 libpcre3-dev libpcre32-3 libpcrecpp0v5 libpresage-data libpresage1v5 libpthread-stubs0-dev libqapt3 libqapt3-runtime libqca-qt5-2 libqca-qt5-2-plugins libqgpgme7 libqmi-glib5 libqmi-proxy libqrencode3 libqt4-dbus libqt4-declarative libqt4-network libqt4-script libqt4-sql libqt4-sql-mysql libqt4-xml libqt4-xmlpatterns libqt5concurrent5 libqt5designer5 libqt5help5 libqt5keychain1 libqt5opengl5-dev libqt5positioning5 libqt5sensors5 libqt5webchannel5 libqt5webengine-data libqt5webenginecore5 libqt5webenginewidgets5 libqt5webkit5 libqtcore4 libqtdbus4 libqtgui4 libre2-4 libreoffice-avmedia-backend-gstreamer libreoffice-calc libreoffice-draw libreoffice-gtk3 libreoffice-impress libreoffice-kde5 libsane-hpaio libsmbios-c2 libsnapd-qt1 libspectre1 libstemmer0d libsuitesparseconfig5 libsynctex2 libteamdctl0 libtinyxml2.6.2v5 libu2f-udev libuniconf4.6 libvisio-0.1-1 libvncclient1 libwayland-bin libwayland-dev libwhoopsie0 libwvstreams4.6-base libwvstreams4.6-extras libx11-dev libx11-xcb-dev libxapian30 libxau-dev libxcb-composite0 libxcb-damage0 libxcb-dri2-0-dev libxcb-dri3-dev libxcb-glx0-dev libxcb-present-dev libxcb-randr0-dev libxcb-render0-dev libxcb-shape0-dev libxcb-sync-dev libxcb-xfixes0-dev libxcb1-dev libxdamage-dev libxdmcp-dev libxext-dev libxfixes-dev libxshmfence-dev libxxf86vm-dev linux-sound-base lp-solve lubuntu-artwork lubuntu-default-settings lxqt-admin lxqt-admin-l10n memtest86+ mesa-common-dev mobile-broadband-provider-info mscompress mtools muon mysql-common neofetch nm-tray noblenote ofono packagekit packagekit-tools pass pastebinit pcmciautils pkg-config plasma-discover plasma-discover-common plasma-discover-snap-backend plasma-framework policykit-desktop-privileges polkit-kde-agent-1 ppp pptp-linux presage pwgen python3-cairo python3-cups python3-cupshelpers python3-dbus.mainloop.pyqt5 python3-debian python3-distutils python3-lib2to3 python3-olefile python3-pexpect python3-pil python3-ptyprocess python3-pyqt5 python3-renderpm python3-reportlab python3-reportlab-accel python3-sip python3-software-properties python3-xapian python3-xkit qapt-batch qdbus qml-module-org-kde-bluezqt qml-module-org-kde-kconfig qml-module-org-kde-kcoreaddons qml-module-org-kde-kio qml-module-org-kde-kquickcontrols qml-module-org-kde-qqc2desktopstyle qml-module-qtquick-controls qml-module-qtquick-dialogs qml-module-qtquick-layouts qml-module-qtquick-privatewidgets qpdfview qpdfview-djvu-plugin qpdfview-ps-plugin qpdfview-translations qrencode qt-at-spi qt5-qmake qt5-qmake-bin qtbase5-dev qtbase5-dev-tools qtchooser qtcore4-l10n qtpass quassel quassel-data rfkill sbsigntool sddm sddm-theme-lubuntu secureboot-db skanlite software-properties-common software-properties-qt spice-vdagent syslinux syslinux-common syslinux-legacy transmission-common transmission-qt tree trojita trojita-data trojita-l10n ttf-ancient-fonts-symbola ttf-ubuntu-font-family ubuntu-drivers-common ubuntu-release-upgrader-qt ubuntu-report usb-creator-common usb-creator-kde usb-modeswitch usb-modeswitch-data vlc vlc-bin vlc-l10n vlc-plugin-access-extra vlc-plugin-notify vlc-plugin-qt vlc-plugin-samba vlc-plugin-skins2 vlc-plugin-svg vlc-plugin-video-splitter vlc-plugin-visualization whoopsie wvdial x11-apps x11-session-utils x11proto-core-dev x11proto-damage-dev x11proto-dev x11proto-fixes-dev x11proto-xext-dev x11proto-xf86vidmode-dev xbitmaps xclip xdg-desktop-portal-kde xinit xorg xorg-sgml-doctools xtrans-dev zlib1g-dev zsync

Answer 1

Ok thankfully the package manager I am using in Lubuntu, known as Muon Package Manager, has a history list of uninstalled packages and their dependencies; (including those removed via command-line or muon) It showed purging the bluetooth and printer drivers resulted in uninstalling "lubuntu-desktop", purging modem drivers resulted in purging "network-manager", this explains my network manager also breaking.

Your equivalent for muon package manager will likely be synaptic package manager, and hopefully that will provide you with the same history. I had to go through the list manually and install the missing packages.

After reinstalling "lubuntu-desktop", apt gave me this (blue relates to bluetooth):

The following additional packages will be installed:
  bluedevil bluez bluez-cups foomatic-db-compressed-ppds libgutenprint-common libgutenprint9 libkpmcore7 openprinting-ppds
  partitionmanager printer-driver-brlaser printer-driver-c2esp printer-driver-foo2zjs printer-driver-foo2zjs-common
  printer-driver-gutenprint printer-driver-m2300w printer-driver-min12xxw printer-driver-pnm2ppa printer-driver-ptouch
  printer-driver-pxljr printer-driver-sag-gdi printer-driver-splix pulseaudio-module-bluetooth
Suggested packages:
  hplip-cups printer-driver-all gutenprint-locales hpijs-ppds hfsplus hfsutils reiser4progs psutils hannah-foo2zjs tix tk
  gutenprint-doc magicfilter | apsfilter
The following NEW packages will be installed:
  bluedevil bluez bluez-cups foomatic-db-compressed-ppds libgutenprint-common libgutenprint9 libkpmcore7 lubuntu-desktop
  openprinting-ppds partitionmanager printer-driver-brlaser printer-driver-c2esp printer-driver-foo2zjs
  printer-driver-foo2zjs-common printer-driver-gutenprint printer-driver-m2300w printer-driver-min12xxw
  printer-driver-pnm2ppa printer-driver-ptouch printer-driver-pxljr printer-driver-sag-gdi printer-driver-splix
  pulseaudio-module-bluetooth

Now my list of packages that are no longer needed has shrunken to just 9;