My Hampton Bay ceiling fan no longer responds to the remote. The fan won't turn on and the lights won't go on.

How can I fix this without replacing it?

Could be Batteries, DIP switch setting, No power to wall transmitter, bad transformer or receiver. Fan and light are probably OK as both don't usually go at once, unless wiring problem.

Does the LED light up?

Check the dip switches as suggested. Try a different (matching) setting.

Does the fan have pullchains?

Ceiling fan remote controls - help and FAQ- Ceiling Fans N More