Hi Tyla and Welcome to the Board!
Not sure if you're asking for info on what music is played in this cartoon or if it's been made available.
The piece that Mickey and his Orchestra try to play is called "Light Cavalry Overture".
Sadly Disney has not released the scores to any of it's short cartoons. The most we've ever gotten is the music from Mickey's Toontown and Toontown Fair at WDW, which are re recorded versions of the scores to several Disney shorts. This particular piece is not used though. Hope that helps.
Incidentally my favorite part of that cartoon is when (I think it's) Donald is desperately trying to play the accordian, and it just keeps going all over the plays and only makes a "Hee-Haw" sound, albeit, in time with the music. Classic.