How do i recover from patellar tendinitis? is cortisone a cure?

No: No steroid near this tendon , stretch and strengthen hams and quads- will improve over next few weeks with activity modification

Physical therapy 1st: A stretching program supervised by physical therapy usually does the trick. No injections are indicated as a first line of treatment.

Tendinitis: Rest ice patella strap. Ant inflammatories and cortisone can help. Physics therapy is an option