Sounds to me as if their might be a short either in the cable itself, or your monitor is shorting out. Does the BIOS detect the monitor, and your video card? If not, more trial and error needs to be done to resolve the issue. Hold you ear up to the monitor when you power it on, what do you hear?
I checked everything cables monitor and making the card was in properly, it didnt switch back on. I left the p.c and came back to it the next day and it switched on and i had a picture. Then i switched of and left it for an hour came back and switched it on and it powered up but again there was no picture.