Audio Problems

[xguile668]

Hey, I'm still a new user to cakewalk but I've been having a problem lately. If i close out cake walk and open this project i have been working on, the instrument track loses its audio. I can't seem it get it back either, if i want to hear the track i have to make a new drum track and copy the midi notes over to the new track. can anyone help me.

Thanks in advance.