First, a piece of advice: in Xubuntu 18.04, there is a pre-installed application called Web Browser. It is NOT a Web Browser. I uninstalled it via Software Center thinking it was redundant with Firefox around, but it deleted a bunch of things, among them exo something (no idea what those are but they look important), File Manager, Terminal and who knows what else.
This is exactly what happened to me:
When I looked to my installed apps in GNOME Software, I saw a "Web browser" with very little info, so I removed it. GNOME Software issued no warning and I removed exo and half of Xfce (I was running on Xfce). After restart, everything stopped working (no xfdesktop, na panel, etc...).
I consider this dangerous.
Now, desktop is gone, with Super key + R I get the list of installed apps, most of them are still there and launching. Opened Software Center, but when I try to re-install Web Browser, Terminal or File Manager, I have an error mentioning unset dependencies.
My question is: how can I get back what I deleted with no Terminal? Of course no back-up, it is my father's PC, I am managing it for him (and not doing a very good job it seems).
Much appreciated. And for the love of God, DO NOT delete that ill-named Web Browser app.