x3 newbie- actually done this since 8.5. anyway, I thought I would try this comping thing that I kind of understood. so I set it to go to 5:00:00 and start over without hearing the previous tracks and storing it in the same track. I worked forever at this, mostly practicing etc as it is a complicated piece. when I went to listen to it- all there was left was a little bit of stuff after 5. The rest is gone. I did a search and found these file pieces but n\it says old version, incompatible. What happened. so much for comping. didn't learn anything new today.
What I want to know is what I did wroing and where are those files?