I recently had Kubuntu 7.04 installed on my Toshiba M45 laptop almost successfully, as in my sound once worked but then it stopped after I installed a lot of other things. So I googled my problem and saw a user with the same model laptop with the same problem, and someone suggested to downgrade udev. So I got an earlier version and uninstalled my current udev...which might have been a bad move. I then tried to install the other udev but it wouldn't let me. I then restarted my laptop and logged in using my password, but then the screen went black and put me back on the login screen. I'm fairly new to linux so I might need some detailed instructions as to what to do next. I have a sense of Unix commands and figure I might have to use recovery mode. Help?