No signal to monitor.

havent been able to get a working monitor working. i had a screen and all of a sudden after moving my office around and reconnecting all of the hardware for my puter i was getting no signal. today i replaced the vga card because the monitor works fine on my lap top. with out the monitor i have tried blindly to go in at startup to safemode by pushing f8. from there i waited until the hard drive was winding down in activity and pushed windows and r at the same time. my next move was control shift tab, and after that i went to alt plus s and finally i pushed the left arrow button and enter several times but had no resolve. this afternoon at the computer place where i bought the vga card the technician had my system working with his monitor. i had my monitor with me and i should have insisted on trying it but given the fact that it works fine with my laptop and his worked fine with my system i didnt bother taking it out of the car. i have tried every combination for hooking up the system to its hardware and i have refreshed all of the devices connected to it by unplugging them and reinstalling them one by one. if there is a preferred order for connecting periferals will you please include them in your reply. a friend once fixed this problem for me and he stated it was very simple but you couldnt convince me then, as i struggled some time to figure out on own, and cant convince me now, as i am struggling once again.