I want to get my door lock remote working again....

[acarsme]

1997 Civic EX
My remote door lock hasn't worked for quite awhile and I'd really like to get it back. My remote is pretty beat up looking, and I have never tried replacing the battery because...well, the red light still flashes when I hit a button. Is it possible something is defective with the unit inside the car, or is it most likely a remote or battery issue? Thanks.

 

[DTvn]

Did you by any chance install a new radio? If you did it won't work

 

[acarsme]

I only remember installing a Honda CD player as my Civic came with a tape deck originally. But I can't recall when my door remote stopped working in relation to that. But my original radio remains up top.