I can't boot into a usable system after updates. What should I do?

Don't panic!

The chances are great that your personal data is fine. Please try the steps below. If anything doesn't work or seem right, you can bail with no risk of data loss.

1. Obtain an Ubuntu installation medium. (LiveCD or LiveUSB)

2. Turn off your system, insert the installation medium, and boot it, selecting "Try Ubuntu" when the option comes up.

   

3. Click "Home Folder" in the Unity launcher. In the window that then appears, you will see a "Devices" section, under which are images of storage devices (both in your computer, and attached).

   

4. Select each device, in turn, until you find one that contains folders like bin, boot, cdrom, dev, etc, and home. Select home.

   

5. In this folder, you will find the home folders of all users of your unbootable system. Copy all important data in these folders onto the internet, onto a portable usb drive, onto another hard drive, or even onto Ubuntu One. After you are done, click the arrow button next to your hard drive to unmount it.

   

6. Click the Install Ubuntu button to begin reinstalling onto your machine.