Layers in GIF lost after Save

I start from the assumption that I'm new to Photoshop, I was working on a gif, modifying some layers, everything was going well, I did some retouching and then I saved, until I did the work as usual, saved and turned off the pc, the day after I open the Photoshop file and find that all layers are gone except one named background, I tried to see everywhere but there is no trace of my past work, no error message, just level 0 and that's it, someone knows what has happened and especially if you can do something?

[Subject renamed for clarity by moderator. Was "Photoshop".]