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I have a hand me down laptop that I don't know the windows password for. Ubuntu worked fine until I allowed it to update. Sadly, it got stuck for hours then shut off and when I turned it on it will not boot into the new Ubuntu, the old Ubuntu, or Windows (since I don't have the password). Should I delete everything, get a live cd, and install Ubuntu again? I tried to load ophcrack to get my Windows password but it will not boot.

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What error do you receive when trying to boot up? If it's long, don't bother to copy it all down. –  Vreality Feb 15 '13 at 2:41

2 Answers 2

If you have documents on the hard disk that are important and don't exist anywhere else, then you should boot from a live CD/DVD or live USB and back them up.

Then, you can probably fix the problem. As Vreality says, you should describe to us how it fails to boot. Here are the most likely possibilities:

It immediately fails when you select Ubuntu.

If that happens, reinstall GRUB to the MBR:

It freezes on the Ubuntu splash screen.

If you see the Ubuntu logo and colored dots in the middle of a purple screen, and it never gets past that, then you'll have to provide more information. Press Escape to reveal what's "behind" the splash screen. If that doesn't work, try pressing it earlier--right when that screen appears.

It boots to a black screen.

Press Ctrl+Alt+F1, log in with your username and password (don't worry that nothing appears on the screen as you enter your password). You should get a prompt that ends with $ _ (where _ is a blinking cursor).

Now repair your system and finish the update:

sudo dpkg --configure -a
sudo apt-get update
sudo apt-get -f install
sudo apt-get -y upgrade
sudo apt-get dist-upgrade

(You can attempt to switch back to the GUI with Alt+F7 but it won't immediately work; the easiest way after those commands complete is to reboot. To do this safely, press Ctrl+Alt+Delete--that reboots when you're in a virtual console--or run sudo reboot.)

If you cannot get a login screen, or running those commands don't fix the problem, see:

If fixing this proves difficult, you might want to reinstall.

An alternative would be to boot from a live CD/DVD or live USB and chroot into your system, mounting the necessary filesystems and trying an update. I would have to attempt this on a recent Ubuntu release to write a good guide for it in your situations, and I would also need more details about the problems you've had.

But the procedure will be similar to the methods detailed here; you will be performing different actions than installing a kernel, though. (Depending on the nature of the problem, which would be revealed by a more detailed description of what happens when you try to boot, perhaps these.)

A general point about lost passwords.

If you lose your password to any system (Ubuntu, Windows, or anything else), it is overkill to try to crack the password. Unless your passwords are very easy, this will usually fail or at least take a very, very long time. Furthermore, unless disk or home directory encryption is used, nothing bad comes from the password being lost forever. Instead of trying to recover the password, you should instead reset it to something new.

If you ever lose your Ubuntu password, you can reset it with one of these methods.

Resetting Windows passwords is beyond the scope of Ask Ubuntu, but you can:

  • Search the web. I recommend searching for sethc.exe (which is involved in one of the most common methods).
  • If you have trouble, ask somewhere Windows is supported, like Super User.
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You have a few options, some of which will work depending on what's broken. If you can get in to Ubuntu but it doesn't work the way your think it should, then you can try and log in without graphics. To do this, you can boot Ubuntu and then press Ctrl+Alt+F1. After that, just log in with your normal username and password. If you can log in there, then you can try to run:

sudo apt-get update; sudo apt-get upgrade

If that doesn't work, your Xorg may be broken; you may be able to fix it with this:

sudo dpkg-reconfigure xserver-xorg 

If that doesn't work or you can't log in, then try the following:

Load the recovery option if you can still load GRUB (I assume you can if you can load Windows). Then, select the recovery option. Note that you may have to select "Advanced Options for Ubuntu" and then something like "Ubuntu, with Linux 3.5.0-23-generic (recovery mode)" Finally, you can attempt to fix it by enabling networking and then reconfiguring the packages (both of these should be menu options in the recovery menu).

If neither of the above work, or you don't feel comfortable trying them, then you can get an Ubuntu Live USB or CD (I'm assuming you can if you could get Ophcrack) and then boot into that. Then, get a flashdrive, hard drive, or online storage service (you could use mega.co.nz and then use goo.gl or a similar service to shorten the URL to something you could write down) and backup your files there. Then, just install the latest Ubuntu and then copy the files back over after installing it again.

If you want to try and get Windows working again, you can change the password instead of trying to recover it with Ophcrack. chntpw is the typical way to do this. If you can get a live USB with Ubuntu on it, then you can take a look at this guide (although it is a bit dated, so it'll look different on a newer release)

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