Look sorry mate I don't know much about computers I'm not stupid and I have come on here for a bit of help not to be patronised. There are only two slots one of the vga slots and a dvi slot and thats it. then theres a long pink one.
How am I patronizing you? You just told me that you didn't unplug the monitor from the back of the computer, yet somehow you were able to take it to a local shop. That is impossible unless you carried the monitor and the computer into the shop while they were still connected.
You have not given us enough information to help you any further. We don't know if you motherboard has onboard video or not. If you have a video card AND onboard video, then you have more than one place to plug in your monitor.
You can lead a horse to water, but you can't make him drink.