Many possibilities. R.I.C.E. Rest, ice, compression, elevation. Immobilization with a cast, splint or brace may be needed in the initial phase of recovery. Oral anti-inflammatory medication may help with the pain and swelling. Once improved, mobilization and physical therapy can help restore strength and function. Healing times may vary.
Evaluation. The first step would be to determine what treatment you have or have not already had.
Ice. If you are not in a cast, apply ice packs , 20 minutes out of every hour. Take an anti-inflammatory medication, if you can.