Premier Elements 14, cannot restore saved file

I was working on a file within Premier Elements 14 this morning and now when I try and restore the saved file it says "this type of file is not supported, or the required codec is not installed".

Is there a solution to this, it won`t load any of my other saved files now which were all edited within Elements 14.

Is there anything I can do to resurrect this as one file has taken me ages to finish and I now cannot get it back.

Many thanks.

Paul.