screen resolution and sound problems

i haz two monitors with 1024x768 on each on old graphics card  nvidia geforce gt 9800

i started messing with options in game to try and fix the missing game screen on the sides ... it didnt fit the 1024 width

game is running from steam and is full screen regardless if i tick the button for it in options or not

if i try to change the resolution it goes to windowed mode 1280x768x and is split across two monitors...

and i loose the option to go back to 1024x768

fullscreen on/off works now after changing the res *point of no return* but the resolution doesn't fit now ... HELP how do i get the default back ?

on the side note... sound is gone i think i broke it with changing the resolution and fullscreen/windowed  mode  .... arrgghh  qq