If you have gone over your current set up (both code and hardware)- double checking everything, and it still doesn't work, you'd have good reason to suspect that it is broken.
If it is still working and you have gotten something wrong in your current set up, it would be the things that you have changed and may have bumped. Get a multimeter and check that voltages are expected values.
If you still can't get it working, you'll need to buy a new one. If the new one works, than you'll know for sure!