It's my first question here, so please don't be harsh (I know you won't, just saying). ;)
I'm working on Ubuntu 13.10 as I updated it from 12.04 recently. Previously (when using 12.04) when I tried to install properitary graphics driver I had an information that Ubuntu will work in low graphics mode and I also had option to restore previous display settings. In 13.10, after update, I tried to do the same. I set the graphics driver (in system options somewhere) to the ATI [...] proprietary [...] (fglrx-update) or something. After reboot I was unable to log in properly. Well, I could log in, but the only thing I could do was to move mouse pointer on the blank screen. I looked up things on the internet (including askubuntu) and removed fglrx* packages though the TTY console and made things even worse. Now not even logon screen appears. Just mouse poiter.
lspci command tells that my graphics card is ATI Mobility Radeon HD 5430/5450/HD5470, if it would help.
What should I do now?
EDIT: I found the solution. In Recovery Mode (you should press Shift key while booting and then select advanced) I used a tool to fix broken packages.