Several saved files are missing

[rllron]

 Greetings....
I have been using Gimp for awhile and have several photo files saved in the program.  However today I can only open a few of the files, the rest are no longer visible.  When I select 'open' file at the bottom it shows Select File Type (Automatically Detected).  It won't let me select 'Show All Files'. 

 
I would appreciate some assistance.

[Ofnuts]

By default the open dialog show all the file types with a file type that Gimp can open.

I don't know why you can't select "Show all files" but it is rarely useful. DO you see the files in that directory if you use your file explorer? Also, are you sure that the files where saved in the directory where you look and not in some other one?