when entrance to desktop, only show terminal
 

hi ubuntu master, i use ubuntu lucyd 10.04.
i try to change splash screen and login manager,after that i reboot.
when entrance to desktop i only found terminal and nothing else. i very confuse why this happened? help me please, maybe any command from u, to i use.
thx

Welcome to LQ
Perhaps you can tell us exactly what you did, before things went wrong.
Did you make a backup of the files you changed?
If yes, put them back.

Regards

nothing, i just do it. i don't know which one, make wrong things. i change login screen, through login manager in preference. then splash screen through art manager. after that, my PC is not responding,So i do direct reboot. when i turn on again, i only show terminal before login. then i write command exit, so it's succes to login. after login, i only found terminal too.
i didn't make the backup, i just have a installer CD.
can explain how to back up a linux?

You may as root, on this ubuntu box try to reinstall gdm application.
The command is: aptitude reinstall gdm