The cable's probably for ****. If the problem's at the computer end of the cable, try screwing it in better, checking the pins, etc.- this happens relatively commonly (I get it occasionally, due to the fact that my monitor cable's hanging about an inch above the ground where people like to put their feet.), but all it takes is a little common sense to fix
If the problem's at the monitor end, you probably pulled a couple wires loose already inside the monitor, and you're gonna have to take a screwdriver to the casing to fix anything. Duct tape is not a solution, you'll probably end up yanking out the rest of the wires.