Hi texmexgal,
Chances are the remote is now programmed to a different address than the receiver. You just need to try each address on the remote until you find the one the receiver is set on.
With that remote/receiver combination, codes 000-007 are available.
1) Hold down ENTER and MUTE on the remote until the Sat/TV/Aux buttons flash in succession.
2) Enter the first code (e.g. 000). Press ENTER on the remote and watch for a light to flash on the front of the receiver, indicating a successful match.
3) If nothing happens, repeat steps 1 and 2 until you have a successful match. Try codes 001, 002 ...all the way to 007.
Once the remote/receiver are paired back up, if you need to change the address again (e.g. to prevent interference with a neighbours remote), press OPTIONS 6-4-3-2. Then hold ENTER and MUTE again, enter the desired address (000-007) and press ENTER to pair the remote and the receiver.