Help me PLEASE!

i have winxp pro os. yesterday i was messing around with the screen resolution setting (i'm using onboard graphics). when i turned up the screen resolution to 1200x1080 and up the refresh rate to 70hrtz (i know default rr for 1200x1080 is 60hrtz) the screen turned off for a brief second or two (which is typically normal) but then the screen never comes back on. it gives me the blank screen and the monitor says "please adjust pc setting" but i can't see anything! i tried reboot but as soon as the login screen comes on the screen goes blank again and i get the same message from my monitor.
i am able to bring up the login screen and log into my personal account by randomly clicking, so the programs do work but how do i set the screen again when i can't see anything?

is there something wrong with my onboard graphic chip? how (if possible) do i go back and revert my screen resolution? can i set screen resolutions using the keyboard?

any help or suggestions would be appreacitated!

 

Boot into Safe Mode (tap F8 while booting) and select a lower screen resolution.

 

Thanks for the feedback. I'll try it!