I bought a used 2008 ford escape. No owners manual. How do I reset the keyless entry. I don't know the original code.

Did you mean the key pad on the door? if it is then you need to track down the original owner to give you the factory code then you can program up to 3 codes.
give the local dealer a call to see if they can run the VIN number for a factory code, they may charge you a fee.
if you bought it from a dealer then they must take care of that for you at no charge.
otherwise you will need to replace the key pad.

THE DEALER CAN PLUG THE CAR INTO THE COMPUTER AND GET THE DOOR CODE FOR YOU..IT IS THE ONLY WAY