M4a broken!!!! Help !!!

Hi guys, I have a broken record file (m4a) using iRecorder Pro. How to fix it ?????

The problem is I can't open the file it shows me "0" duration it contains very important data from my lecture, it happened when I paused the record then I took some shoots and I wanted to resume the record but it couldn't so I thought it has been ended so I start a new record but I need the first record cause it's very important for my study. Any ideas to fix it ??