Open the file with a standard text-editor ,(you'll see a lot of "spaghetti", don't bother), now look at the very first couple of characters, if it is an image file it will have a standard set of characters.
Open up your own known BMP,JPG,GIF and whatever to see which set matches.
rename the file as (picname).
However , if it is not a genuine pic but a compressed PNG (or whatever) then you have a problem : you must find a viewer (like ACDC) that can open the file (remove the extension) AND save it as.
If the image is part of several files of a program then just copy the file as "data"-file.
If you have opened enough pics to see the difference between pics and compressed files then you can open the .000 file as .txt file and see if the file is a pic or something else.
Hope this solves the problem, please let me know and don't just disappear.