Missing work

I went on acrobat to complete some personal training work a few days ago to finish off my level 3 (it was 90% completed) and have come to find that my work is completely gone. The work is there but all the boxes are empty like I had never opened it. I have done everything in the last 2 hours to try and retrieve it but no luck. Where could this have disappeared to?

I had this work on my phone and on my laptop so it has to be something to do with acrobat. Can anyone help please.