I had this glitch before hand where only the main menu music would play how do i go about fixing this?
What OS do you have? XP or Vista? Is your game patched? Are you using some mod? Have you tried updating your sound drivers?
Try this: Go to Start -> Run, type DxDiag, click OK, wait for the application to fully load, go to Sound tab, reduce Hardware Sound Acceleration Level down to Basic, close the application and try running the game. Sometimes this helps with sound/music problems.
Also, you can try deleting your options.cfg file to force the game to revert everything to default settings and see if that fixes the problem. You can find that file in your Bridge Commander folder (C:\Program Files\Activision\Bridge Commander by default).
Well it started right after i installed a mod cant member which one it was.
In that case, I suggest you to uninstall the game, manually remove all residual files and folders (mods are bound to leave some) and make a clean reinstall. Don't forget to patch the game. Now, test the game without adding any mod and see if the music plays normally. If it does, start adding the mods one by one and test the game each time. This should allow you to find which mod exactly is causing the problem.