Why would my taste buds be gone after I have surgery?

Depends. If the surgery involved your sinuses it would be fairly common to have a temporary alteration in your sense of taste which is closely linked to your sense of smell. Some medications and illnesses can also impact this. If your surgery was not involving the nasal/sinus area and you haven't changed meds recently, a visit to an ENT doc would be a good idea to figure out what is happening.