Display settings launch prob

Hello there
I play wotlk and today i changed my screen so my ingame resolution was changed to widescreen aswell now im back to my old screen and because of the latter ingame settings i cant start the game to change them back ,
"Failed to find a suitable display device"
its what i get when i try to run it
Also i tried the good old delete interface/cache/wtf it didnt work at all
Please help me with this i need to do arena later today is there a way to reset settings without downloading game again???

try to open .../WTF/config.wtf file in e.g. notepad and edit values

SET gxResolution "1920x1080"
SET gxRefresh "60"

according to your display capabilities.