How to reset MacBook Air that is booted but shows no screen? I was using my MacBook air after returning home.  The network was down, so I put it down, closed the lid, and went to reboot the router.  Upon returning to my MacBook Air, opening the lid, nothing displays on the screen.  Pressing the power button does nothing.  I've now attached it to a charger, but still nothing happens, other than the yellow light to indicate that it is charging. The apple on the top of the laptop is not illuminated either.

How can I get the computer to work again?  Is there a way to force it to reboot?  It seems it is booted and either asleep and won't wake up or awake, but not displaying the screen.

Should I just let it run until the battery is dead?  With no display, I would think that would take a really long time.
Apple advises first trying: Hold down the Power button for 10 seconds.

If that doesn't help, do a Power Manager (SMC) reset. No problem.

See this Apple support page for directions for specific Intel machines:
http://support.apple.com/kb/HT3964