Change the voice: He helped me do it.

Help/See + object + infinitive/bare infinitive থাকলে passive voice এর বেলায় help/see এর জায়গায় এদের v3 form হবে এবং Help/see/teach এর পর ব্যক্তি বা বস্তু থাকলে verb এর base form বসে অথবা to + verb বসে।

যেমন:
Active voice: He saw me do it.
Passive Voice: I was seen by him to do it 
Active voice: He helped me (to) do it.
Passive Voice: I was helped by him to do it.