If your saying your radio no longer powers up, you need to start by checking fuses.

is your radio stock or aftermarket? if your radio is aftermarket do as Zack suggest and remove the radio and check on how the aftermarket harness is tied into the factory harness.

make sure to inspect each connection.

if you have an aftermarket radio you should have a harness adapter that should either have soldered or crimped connections, this adapter should plug into the factory harness

many time people get cheap and cut the factory harness and use less than desirable splice connections.

as a warning if you have an aftermarket radio and your having problems with it, make sure to disconnect the negative battery cable before removing the radio to inspect how it was installed.

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2002 Ford Ranger 2 Dr Standard cab 2.3 5 SPD 7.5 373 gears