my 2001 chevy impala sound stop working

With or without amplifier?

Also is it an SEO model unit, Anyway in either case Have the built-in amplifier checked out-your audio comes out of the amp then to the speakers

That depends on whether there is an external amp or not, ras. If it doesn't have an external amp, then the problem can be any number of things.

The problem can be any number of things with an amp, also.

it has an amp. n the trunk

Start troubleshooting and then let us know what you got-

Check the amp. Make sure it is receiving power and powering up. Make sure the inputs and outputs are properly connected. Make sure the wires aren't broken anywhere. Make sure it is receiving preamp out signals. See if is creating speaker out signals. See if the speakers are receiving inputs.