My computer won't recognize my monitor after unhooking for a couple of hours

[Guest]

This will sound strange. I have a powerspec computer and sceptre monitor. I unhooked everything to move it, and now the computer will not recognize the monitor. - light on the monitor flashes but not display - computer is clearly doing start up. Everything is hooked up right. I remember when we originally hooked it up we had the same problem, and the store told us to do something that worked. I can't remember what that was???? Any help?

 

[house70]

is it hooked to an integrated video port, or a discrete graphics card?
More importantly, does the PC have both or just one?