Video card problem in my computer

I was cleaning the motherboard recently and when I out it back, all I can. See was nothing. But the computer is turning on successfully. The keyboard and mouse LEDs are turning on successfully. So I forced shutdown by holding power button until computer turned off and then just rechecked all connections once. I found nothing but after I turned the PC again, monitor came up but showed some random colors. I opened the video card again and placed it. It is okay now. But I am worrying will the problem persist again. I will not be here all the time and some other people use this PC and who cannot actually handle these things. Any reliable permanent solution?