Ok, the problem is i wanna let the music keep on going when a event

They've asked a question before, and it's been established that they're using RM2K3. --- I don't see what the "Erase Event" is for, to be honest. I haven't done anything in RPGMaker for years now, but I don't think it's needed. Heck, that might even be the problem.

I didn't know what version they were using. Erase Event is helpful if you have someone talk to you then leave. You erase his event so that you can still walk around and do stuff and now the event is officially erased. Saves switches and variables.

<> Play bgm = forebonding.bgm <> Erase event

Don't tell the event to play the song again! Just tell the area you go into to set the starting bgm as the song you want it to keep playing. If it is an area where you went into preveously then copy and paste the area with a different starting music. How simple, and if you plan to walk around, then it is perfect becuase you will go into a building and when you exit it then it takes you to the normal area with the other starting music or if you leave then you should have it set just like the building to take you to the original instead of the copy. That is incase after the event you want another song to play.