Can you tell us a little more about the Mac that you have?
Is it an iMac (built-in video)? or a laptop, such as a MacBook?
You mentioned something about "mini mac", so it could be a Mac mini? That would have a separate display - the mini is just a small box, where everything connects.
Or, is it a tower (called a PowerMac)
If you have a separate display - is it a flat panel? or an older CRT display (which means that it has a CRT tube, making the screen quite large, and heavy, especially when compared to a flat panel, or LCD display) Which do you have?
One Mac that I use sometimes seems to lose track of the display. If that's what you have, press and hold the power button on the Mac. It will shut off after holding the power button for 5 seconds. You can also simply unplug the power cord, if you need to, at least for this one time. Press and release the power button to turn the Mac back on. That may get you going again.
Last edited by DeltaMac; July 28th, 2012 at 09:53 PM.
Reason: Added some other questions about the display...
Serendipity is a lucky guess !