Cant boot pc blackscreen fan runs

Hello, DJ..

Can u pls help me to fix our PC? coz it does have a black screen even i restarted it..
i mean.. when u turn on the CPU.. nothing happens just black screen..
i think it happens because i do something in the CMOS Setup
Because i made some changes in it.. cant remember it all but i put sumting into turbo and save the settingusing F10.. then it restarted and cant boot up.. it's just blackscreen.. the fans are working, the lights.. but just plain ol blackscreen.. think u can give me answers to it? i have tried numerous websites and forums to answer my problem.. but i think there is no people that does have the same problem like minehope you answer sir... ahhmm.. there is still one thing.. my PC is running on windows XP sp3..