I got instant rt elbow pain for day and vanished immediately next day without medicine what is the reason ?
Unfortunately not enough information to provide you with an informed answer. The good news is that the pain did not last and so not likely something to be concerned about unless it becomes a recurring problem. Muscle, tendon, bone, nerve are all possible sources of pain around the elbow.
Character of pain, location of pain, and any associated features can help distinguish which is most likely.