How can I fix my Toshiba harman/kardon Laptop PC?

Turn it off for about an hour, then turn it back on.
Does it power up and is the display on?

Does it turn off after some time? With the fan making more noise than they should do?

If it power on normaly but turn off by itself after some time, it may be overheating and get turned off as a way to prevent damage.

Make sure that the air vents are free of any obstruction.
Open the case.
Check the CPU heat sink. Make sure that it's free of any dust accumulation.
Also, make sure that the air duckts are free of any debrit and other obstruction.

Electro
October 2013