I have this amp installed in the car i bought but the amp doesnt turn on so my questions is how can test the amp to see if the amp still good?

Swap in a known good amp and see if it works is a quick sure fire test. Other than that you can use a DC Voltmeter to test the wires. You should see source voltage on the power line when compared to ground. Check the Power Wire to the Ground Wire, again you should see source voltage. Also check the remote wire to ground, again you're looking for source voltage. If you saw source voltage at all measurement points the power, ground and remote circuits are good. The remote wire measurement requires the radio to be on. The trick to this kind of measurement is to realize it's a comparison. You are comparing the voltage of one lead (point in a circuit) to another. If your reading is 0v the voltage is the same in both points you're measuring. An incomplete circuit will have source voltage to the point of the break; example: of you connect a battery to a lightbulb when you complete the circuit the lightbulb will light, if you cut the wire from the positive terminal to the break will be showing source (battery) voltage when compared to the ground side. Swap in a known good amp and see if it works is a quick sure fire test. Other than that you can use a DC Voltmeter to test the wires. You should see source voltage on the power line when compared to ground. Check the Power Wire to the Ground Wire, again you should see source voltage. Also check the remote wire to ground, again you're looking for source voltage. If you saw source voltage at all measurement points the power, ground and remote circuits are good. The remote wire measurement requires the radio to be on. The trick to this kind of measurement is to realize it's a comparison. You are comparing the voltage of one lead (point in a circuit) to another. If your reading is 0v the voltage is the same in both points you're measuring. An incomplete circuit will have source voltage to the point of the break; example: of you connect a battery to a lightbulb when you complete the circuit the lightbulb will light, if you cut the wire from the positive terminal to the break will be showing source (battery) voltage when compared to the ground side.