Recently I ran into a problem where I needed to change the file extension of some Windows files from no extension to .JPG. Someone sent me a bunch of files, but for some strange reason they had no file extension, even though they were images! After adding the .JPG extension to the end of the file, I was able to open the images.

There are many more reasons why you need to rename file extensions. I will show you how to change them one by one if you have a small number of files. If you have a lot of files, you can also rename file extensions in batch.

If you have a file with no extension, Windows will probably assign a generic icon to it. When you try to open it, the Open With dialog box will appear, giving you a list of programs to choose from.

It is obvious that Windows cannot determine which program should open the file because there is no file extension for the file. In order to change the file extension for the file, you first need to be able to see the file extensions in Windows. You can do this by going to My Computer, then to Tools, then Folder Options.