Peace be upon you. According to Ayatollah Khamenei, if your forehead touches the ground during prostration and then rises involuntarily, you must place it back on the ground and recite the remembrance of prostration; all of this counts as one prostration. According to Ayatollah Sistani, if your forehead rises involuntarily before or after the remembrance, and if it happens during the first prostration, you should perform the second prostration after sitting upright. If it happens during the second prostration, you can continue your prayer without any issue. If the forehead rises involuntarily and then returns, it does not count as two prostrations. However, if the rise occurs before the remembrance, it is preferable to recite it after returning, but not with the intention of it being a part of the prostration. May you be successful in all good.