Is there some sort of fuse protection? You never specified you model. If that's blown that could be the problem and easily fixed. You can get a new one at radio shack. Worst case efforts on your part (not much): take the tweeter out if possible and peek in cabinet to see if any wires may have come loose. If its not a fuse, or a loose wire, or a damaged/blown xover part, its probably blown. You could take the tweeter out and hook it directly to the output of the amp just to check, bypassing the xover. (this would mean snipping the 2 wires, no biggy, crimp them back to the main leads when done with some connecters from radio shack, $1.49 for eight). Just play some material that you know has no low frequencies for awhile into the tweet and no damage should be done as you check. Or it may be time to upgrade to some new speakers? Use the remaining one for a center channel? I don't know the speakers but a tweeter change is possible, not always, although you'll want to change both.