macbook Pro not being detected by 2209WA

I recently sent my macBook away for repairs, it was only software problems, the engineers it seemed simply uninstalled and reinstalled the software. Since I have had it back, I cannot get it to detect my Dell 2209WA. It was fine before. I am using a mini display port adapter with a cable (not sure what the cable is called). Nothing has changed, I have pulled out cables at each end, restarted macbook, detected displays, nothing.

When I press a button on my monitor it says "there is no signal coming from your computer. Press any key on your keyboard or mouse to wake it up or press the input button on your display to switch to another source"

The display is currently on auto detect, have cycled through options, still not being picked up.

Any advice?

Have you tried using a different cable? That might fix the problem.

I have, no joy. I have connected the MBP now to 2 monitors and it doesn't work with either of them. It flashes blue for a short while as if it has detected the monitor but then nothing happens. I think there must be something wrong with my mbp

Take it to an apple store and see if they can get it to work with a monitor there.

There are two things you can do:

1) Make sure the MagSafe AC adapter is connected to your MacBook before connecting it to an external screen.

2) If that doesn't work, take it back to the Apple store and hopefully they can fix it for free if there's a problem with it.