What will happen when we wrongly accepted stalemate and thereafter 02-03 seconds we noticed it was not a stalemate but a clear win?
According to the FIDE Laws of Chess:
5.2.3 The game is drawn upon agreement between the two players during the game, provided both players have made at least one move. This immediately ends the game.
However, the annotations to rule 5.1.1 state:
Particularly in junior tournaments it can be discovered that one player accepts he was mated to discover later that he could prevent the mate. If a result is reported by both players that can be accepted. Where a player announces mate and immediately shakes hands only for it to be discovered seconds later that the move played was not mate he should not be given the win despite any handshake.
I would tend to think that a false stalemate should be handled like a false checkmate, and the game should be resumed if the error was discovered within seconds.