If you are having a problem with your ceiling fan remote, when asking your question, please state whether or not the fan has pullchains. Fans that have pullchains AND remotes, the remote can be bypassed, which will determine the source of the problem. If you bypass the remote and receiver and the fan now works, buy a new remote/receiver kit, available at any place fans are sold, or just use the fan without a remote.
If the fan does not have pullchains, the problem is usually either the remote or receiver. If the red LED lights up on the remote when a button is pushed, usually the problem is the receiver. To obtain a replacement receiver for such fans you must contact the manufacturer. See: Hampton Bay fans.