only half the instruments are playing after corrupted file

hi there, i was working on this project (no nicking please) and while it was playing I tried to open the timeline, not sure if this is significant. musescore immediately crashed and once reopened it said it was corrupted (in bars 291 to 293 the harp parts got a bit screwed up). now when I press play, all I can hear are percussion and harp parts, any ideas why? is this a common bug? and most importantly, how can I fix it!

thanks
josh