<!-- from fixya rte -->Tweeter no sound but speaker no problem - Audio Players & Recorders

In the most general, basic sense, I would be assuming that this is just one speaker and not 2 with this problem, or 3 or more.
Only way to get the ball rolling is pull the tweeter from the cabinet, checking to make sure all wires are connected at the tweeter and inside the speaker.
If that is the case, then you would need to determine if this is the tweeters fault, or its crossover (thing that divides the sound into whats right for the woofer and what the tweeter wants).
If you have a multi-meter, you would disconnect the wires from the tweeter, set the meter to ohms and touch a probe to each speaker terminal. No action means burned out tweeter, 100% action means burned out tweeter, a reading slightly less than the rating on the back of the tweeter (for instance an 8 ohm tweeter would show anywhere from 6 to 8 ohms on the meter) means tweeter is good.
If you have no meter then take the tweeter from the good speaker and swap in place of the bad one, making sure you respect + and - connections.Its a little risky this way,since if there is something wrong in the speaker it may hurt the good tweeter..(the meter is the safer bet). If it works, then you need a replacement tweeter, if not the problem is either wire connections inside the speaker, or something is wrong with the crossover.