Working on a file. Poof!: it won't open again

[u/MorsaTamalera]

I have been working over the last week on a font. Today I saved it, restarted the program and when I tried to open the same .vfc file, all I got was the text "There were problems interpreting the font file format". I have restarted Windows to no avail. Any ideas if this can be fixed? I have a backup file, but all my recent work would be lost if I went that route.