Unable to open file

[Gabriella Sandoval]

I have been using gnu cash for about 2 months, and like it a lot.
I posted some things on Friday.
Apparently, I may not have saved, so today when I opened it up, it prompted me to save the file.
It asked me to type in a file name, and I made up a new file name so I could distinguish it.
Now - when I open the file it displays this message;  "No suitable backend was found. "
There are many saved versions, and each one has this message.
How can I fix this?

Poppy