Laptop external display not working or blank

In the multi-tasking world that we live in today, many have had to deal with multiple displays or an attached projector to their desktop computer. Many people have had something happen to their laptop screen, and are forced to use an external display. Other people use an additional monitor, or connect their pc to a TV to watch movies. Well, sometimes if you unplug the display a few times, the external display remains blank no matter how you try to resuscitate it. If you have a Windows Vista or Windows Seven PC, the solution is very simple.
Step 1
While holding this key

press letter P twice.
and then release the windows key
Step 2
~If the display is working: skip to step 3,
~if the display is blank: repeat step 1 (you may have to repeat this up to 5 times)
Step 3
If you indeed use only the external display due to primary display screen being broken or just like to use the external display use part A
if you "extend desktop" => have two independent displays that show different things, go to part B,
If you want the same thing to display on both screens go to part C
If you want to disconnect the display go to part D

A:
B:
C:
D: