2. If you (ask) me. I (help) you.

2. If you had asked me, I would have helped you.

В условных предложениях третьего типа (Type 3) в придаточном предложении (if-clause) используется Past Perfect, а в главном предложении (main clause) используется would have + Past Participle.

Ответ: If you had asked me, I would have helped you.