I have recently purchased a version of Sweet Home 3D from Amazon and had been using it for a few days. Saving my progress as I went. This morning I can open the Sweet Home 3D program and create new homes but the program cant open my saved home. I get the error message:

cant opent home
"my_home.sh3d"

I and using:
Version 5.2.2 Amazon Store
Java version 1.8.0_51/64 bit/6.2 GBmax
Windows 7 Professional

Is there something I can do to recover this file? I am not happy that I could have lost my efforts and reluctant to start re-creating my plan in case this is a re-occurring problem.