Make sure your hood and trunk or tail gate are closed, get in the car and lock all the doors.

Turn the ignition key to position I or II five times in 10 seconds and leave the ignition on after the fifth time.

Within 30 seconds, press either the LOCK or UNLOCK button on the transmitter once.
All transmitters must be reprogrammed within 30 seconds.

Switch ignition off, and press unlock.

You're tranmitter should now unlock your doors.

If you are looking to buy a new remote or a used one I just called volvo with my vin and they gave me the remote code used for my car.