Please help MY Monitor doesnt show nothing :[

Hello,
OMG i got a big big big problem my computer is about 5 years old windows xp i got an envision monitor my computer was working perfectly fine when one day i turned it on and THERE no PICTURE on my MONITOR. The compter turn on and everything the fan spins i have cked the cabls over a MIllion times one time i moved it around and miracouslly work but then Someone disconnected the cable and it messd up again so ive tried the same thing i few times but no luck and when i connect te cabl to the laptop it works perfecly fine PLASE help me im jus dying hre please help!! :[