Reinstalling X config file
From MEPIS Documentation Wiki
Use Mepis X Assistant to restore your X server config
If after changing your X server settings (i.e. installing video driver or changing resolution) you find your X server doesn't load (black screen with text only interface) or possibly starts with scrambled graphics, you can re-install the X config file (/etc/X11/xorg.conf) from a live MEPIS CD session:
- Boot the MEPIS live CD.
- Select the Grub menu entry and resolution that works best for you (hit the <F3> key for list of monitor resolutions if "Auto" doesn't work correctly).
- Start the MEPIS X Assistant (mxconfig from command line) from the System > MEPIS > menu
- enter root password: root from a live CD session
- Use Copy Current XConfig on the Repair tab - make sure to use the correct source and destination partitions!
- Reboot to you repaired X server, note that if you have the proprietary Nvidia/Ati driver installed - you will need to re-edit the X config file to use these.
Create fresh xorg.conf file with Xorg-configure