NOTE: Most of this question is now irrelevant. UPDATE 3 summarizes the problem as it stands.

I've been running 12.04 on my Lenovo laptop for one month now (updated from 11.04), and I have not had any significant problem until today. This morning, when I boot, I pass the Grub screen, then I get to the purple loading screen with dots as usual, then for some reason I got to the terminal login, with no GUI. startx gives me a black screen. Ctrl+F7-F8 didn't help either. It's similar to:

After the update today no graphical interface anymore - 12.04

I followed the instructions at the end, to flush the ATI drivers (which I had installed), and fall back to the community drivers. That made me lose the login! Now I just get a black screen after the Ubuntu loading screen. I can still access the console through recovery, and I've gotten into VESA mode once or twice (not reproducible, for some reason). I've tried various permutations of xorg.conf, without success. Xorg -configure fails for now, though I might be able to get it to work. apt-get update/upgrade doesn't improve anything either.

However, both Windows and the 12.04 Live CD still work beautifully, and I know that all my data is still there. Is there any way that I could somehow take the configuration from the Live CD and roll with it? I know that I could reinstall, but that sucks, frankly, especially given that there's no straight-forward way of keeping the home (which, incidentally, is unaccessible from the Live CD)

Thank you.

Update: it seems that the fglrx drivers are still active, even after I've --purged them. From Xorg.0.log:

[    18.235] (WW) fglrx(0): ***********************************************************
[    18.235] (WW) fglrx(0): * DRI initialization failed                               *
[    18.235] (WW) fglrx(0): * kernel module (fglrx.ko) may be missing or incompatible *
[    18.235] (WW) fglrx(0): * 2D and 3D acceleration disabled                         *
[    18.235] (WW) fglrx(0): ***********************************************************
[    18.235] 
Fatal server error:
[    18.235] AddScreen/ScreenInit failed for driver 0

There's also a mention of the "fbdev" module. What is it?

PARTIALLY SOLVED: I've undone the damage from the fglrx purge. I'm still mystified as to why uninstalling the packages didn't kill fglrx entirely, but I've now recovered the prompt. The solution to the DRI initialization error was to add radeon.modeset=0 to the GRUB boot options.

So I'm back to being dropped to a prompt without any GUI. startx gives me a bunch of messages, though no obvious errors. I have little reason to suspect the video drivers, as they worked fine before today. There is no apparent error message in any of the log files.

UPDATE: When I startx, I get an error, Plymounth command failed mountall: Disconnected from Plymouth This is all over the Internet, but I have not found anything that works for me yet.

UPDATE 3: If I press ESC during boot, the splash screen (Plymouth!) disappears, and I no longer have any error from Plymouth. The last error message is: Stopping mount filesystems on boot I can then Ctrl+Alt+F1 to get the TTY1, but startx still does not work. Sadly, the Internet knows nothing about this error message, and neither do I. Help!