my mac stays on a blue screen and doesnt turn on

Safe Boot by restarting your computer while holding down the "shift" key. Safe booting disables all nonessential processes, often times allowing you to start up when you would otherwise crash.

As of OS X 10.5.6 Safe Boot deletes the dynamic loader shared cache location in the /var/db/dyld directory. A corrupt cache here can cause the blue screen crash. Once you restart normally, the cache will be recreated. This should take care of the issue.

http://support.apple.com/kb/HT1564

http://support.apple.com/kb/HT1455

Startup - Blue Screen

Startup Issues - Resolve

Startup Issues - Resolve (2)

Startup Issues - Resolve (3)

I did the following; Safe Boot by restarting your computer while holding down the "shift" key. Safe booting disables all nonessential processes, often times allowing you to start up when you would otherwise crash. It still is blue. Could my keyboard be bad? Does the green light have to stay on the keyboard all the time? It comes on and then goes off. My computer is 7 years old btw