Could you post details like the model number, what you have it hooked up to, etc.
Here is a little troubleshooting guide.
Disconnect all the speakers and see if the power stays on.
If it does, you have a wire or speaker problem.
If the power still goes off, you will have to disconnect the unit, take the cover off, clean any dust and check for obvious burned out component, loose wires, dead bugs, etc.
If that does not resolve the issue, you will have to get it serviced or get a new one.
And please use punctuation and capitalisation. It's much easier to read for us old folks.