Change File Extension in Windows 7
How to Change File Extension in Windows 7
In Windows 7, by default you do not see a file extension.
To change a file extension, you first need to show the file extension. This can be done from Folder Options.
Go to Windows search and run Folder Options
Click on View tab.
UnCheck Hide extensions for known file types.
Now go to your file and you should see the file extension. Now you can easily rename it to whatever extension you like.