The movie is a new Thai movie called Chocolate staring Jeeja Yanin. The theme song of this movie is amazingly moving but, I don't know the band name or song title which is heart breaking.

Heres a clip with the song (At the beginning).
http://www.youtube.com/watch?v=PEW4eg_grrI

Please help.

If you guys respond, that'll be nice enough. As long I'm not searching for this alone.

I just watched the trailer and really like the song too.

I couldn't find anything online for a soundtrack to "Chocolate," so I think your best bet would be to wait until the DVD comes out and most likely a related soundtrack, or post on the message boards at the official movie site asking the same question.

http://www.chocolate-movie.com/board/index.php