Does committing masturbation after Salatul Hajah (the Prayer of Need) affect the supplication's (Du'a) acceptance, and are repentance and two rak'ahs of prayer after ghusl (ritual bathing) sufficient for its acceptance?

Masturbation is forbidden (haram (definition)) and is one of the impediments to the answering of prayers (du'a). Performing two rak'ahs of prayer after committing it is called Salatul Tawbah (definition) (Prayer of Repentance), which is a good deed. However, it cannot be definitively stated that this will guarantee the answering of prayers, as the answering of prayers is among the matters of the Unseen (al-Ghayb).