One month before i was playing cricket a ball hit to my leg. then a lump appeared there what should i do?

Leg injury: If it is just a lump with no pain then it is just a hematoma. If the swelling is in your knee/ankle joint and you have difficulty with movement, then this needs to be evaluated by a physician for any ligament injury. Overtime, this lump should get smaller, given that it persists for over a month, you need to have it examined by a physician to be certain it is nothing sinister.