pc wont restart after power loss

help me!!!

my new computer froze while playing a game. i tried all i
know to fix it but it did not respond to keystrikes or
the movement of the mouse. it also didnt respond when i
tried to shut it off through the front of the computer.
so i then unplugged it from the wall. when i replugged it
and tried to turn it on, nothing happened. the screen
stayed black even thought i had turned the monitor and
tower on.

How can i make my computer work and how can i avoid such
a problem in the future?