Add .mp3 to the end of file names

I moved all my songs off my phone to a flash drive. Then I uploaded them to my new phone, only when they were stored to the flash drive they come over missing the ".mp3" so they are seen as "file". If I rename each file, adding the ".mp3" the file switches back to an audio file and plays just fine but there are 167 songs.

Is there a way to add the ".mp3" extension to all of them at once instead of one at a time?

I'm using my Windows 7 laptop to rename the songs on the flash drive. I selected all files names and right-clicked and hit rename. I entered the .mp3 and it rewrote every file to that one title, but it didn't add the .mp3. What should I do now?

I often use a command in Command Prompt in Windows, it's REN. The purpose is to rename a file or more.

ren oldfile.png newfile.png

But in this case, you need to rename multiple files, then we can make the command like this:

ren * *.mp3

In that, the first * is to declare all files and the second is to change all files to .mp3

Make sure you move all files to a folder and run the command in this folder.

Just run ren * *.mp3 in cmd. You don't need 3rd party solutions in this case

LOL. so you have a bunch of numbered extensionless music files? Well, we can get the extension fixed so you can play the files. Also, once they're recognized as .mp3 files, they most likely will be metadata that can help restore meaningful names. But first things first.

This can be done with a few lines of PowerShell. If you'll please edit you question to provide paths & example names, as well as clarify if all the files are in one folder or a folder with subfolders. Are the extensionless .mp3 files mixed in with other file types?

For the time being, I'll assume the easiest, all files need the extension added & are in a single folder or its subfolders. The code is simply:

( Get-ChildItem 'c:\Music\Folder' -File -Recurse ) |
    Rename-Item -NewName { '{0}.mp3' -f $_.Name }

and for those that value brevity:

gci | ren -N {"$_.mp3"}

and that's it! Your files should be renamed.

Ex Falso free open source audio tag editor for Windows/Mac/Linux can do exactly what you want. Ex Falso automatically identifies all mp3 files as mp3 whether they have an .mp3 extension or not. Just select all the songs in Ex Falso, select the Rename Files tab, click the Preview button to preview the results of the batch rename operation, and click the Save button to batch rename them.

Ex Falso is a GUI application, so you can browse to the files to be renamed and batch rename them wherever they are located. You don't need to move all the files into the same folder.

Ex Falso can also edit song metadata tags in several different ways.