The file format in most cases is determined by its extension, that is, by the part of the name that is to the right of the last point. The extension is used by operating system components and application programs to identify file types and formats of data recorded in them. If for some reason you need to rename this part of the file name, then you can do it in the standard Windows Explorer.
Instructions
Step 1
Start Explorer by pressing the WIN + E keyboard shortcut (Russian letter U), or by double-clicking the "My Computer" shortcut on the desktop. Windows default settings prevent Explorer from showing file extensions. If you have already changed these settings, then go to the next step. If you see only file names without extensions, then in the Explorer menu, open the "Tools" section and select the "Folder Options …" line in it. On the "View" tab of the window that you open in this way, there is a list of "Advanced options" with the line "Hide extensions for registered file types." Uncheck the checkbox for this setting. If the file you need is a system file, uncheck the box next to the item “Hide protected system files”, and in the line “Show hidden files and folders”, on the contrary, check the box. Click "OK" to commit the changes to the settings.
Step 2
Navigate to the folder containing the file you want to change the extension and right-click it. In the context menu, select the "Rename" command and replace the extension with the designation of the format you need. The explorer will ask you to confirm the operation - click the "Yes" button.
Step 3
If Explorer shows an error message, then perhaps this file is protected from any changes. To find out, right-click it and select Properties. In the properties window on the "General" tab there should be a check mark next to the "Read-only" attribute - uncheck it. Click "OK" and repeat the renaming operation. Another reason for the impossibility to change the file name may be that any of the programs are working with it at that moment. If it is an application program, then it is enough to close it and repeat the operation. And if the file is used by any component of the operating system, then you can try to rename it by restarting the computer in safe mode. If this turns out to be impossible, then you can use a boot disk and some kind of file manager.
