External display suddenly wont connect

[speedyfv]

I was using my macbook which is connected by a minidisplay port to hdmi cable to a 24" samsung lcd. I closed my macbook then accidentally moved my bluetooth mouse which turned my macbook back on in clamshell mode, after that my macbook wont recognize i have the external display connected, everytime i plug it in my macbook screen just starts flashing.

Any help?

 

[speedyfv]

Bump, still havent found a solution

 

[dusk007]

Have you tried other displays?
If you click spaces, does the mini View show the extended Desktop?
Do you have by any chance switchable graphics and are you forcing the IGP?