it's possible you dislodged the video card (unless yours in on the MB). AGP slots can be touchy and component fit is not always perfect. Video cards get unseated and it only takes small movement to do this. Remove and reseat it and see if this helps.
Ok i just opened my pc case to clean the dirt and so on , when put back together and turned on right away it says " Monitor Out Of Range" with a pure black screen , and pressing keyboard buttons or restarting the comp doesnt help. I tried putting my brothers monitor considering my monitor might be dead , but still same error on screen , is something wrong with my motherboard ??? How do i fix it please help. All help appreciated.