It's a rare form of the French Defense, which is usually played with the move order 1. e4 e6 and only then 2. d4. Black's 2... Nc6 is atypical.
You lost your pawn because you failed to protect it with e.g. 11. Be3. However, your trouble started with 9. Bb5, since it was very easy for black to repel that attack, causing you to retreat and leave your d-pawn unattended. After losing your pawn, you exchanged your pieces away too eagerly, which is not a good idea when down on material (even only a pawn).
Good recovery, though.
just wanna ask a question what's the name of this opening it's the first time I see it :S
I lost a pawn at the first 11 move but how I lost it what should I play to keep the material even ??
at move 31 and 32 I closed up the queen side pawns to keep the bishop there and lock up his bishop movement
here's the game