PSD files changed into Photoshop.image.21 file type that can't be opened with photoshop app.

I am fairly new to photoshop and but have been working without any issues for about a month or so Recently all of my psd files' format changed into something called "photoshop.image.21" I didn't change any setting so I am unsure what caused this problem. The only thing I noticed was that I had an laert saying photoshop end of file but I was still able to work and edit in the application. Any advice would be appreciated.