How can I cut and trim mp3 files downloaded from youtube?

Windows Media Player itself does not have a built-in feature to directly trim MP3 files. However, you can trim MP3 audio within Windows Media Player by using a third-party plugin called the "SolveigMM WMP Trimmer Plugin." This plugin allows you to cut, split, and trim audio files right inside the familiar Windows Media Player interface.

How to trim an MP3 file with Windows Media Player

1. Download and install the SolveigMM WMP Trimmer Plugin.

2. Open Windows Media Player and enable the plugin through the Tools > Plug-ins menu (you might need to enable the menu bar in Windows Media Player first).

3. Open your MP3 file in the player or through the plugin interface.

4. Use the plugin’s editing interface to add markers defining the start and end points of the segment you want to keep or remove.

5. Save the trimmed mp4 file.

Note that the SolveigMM WMP Trimmer Plugin is not free but it has a 21-day trial with limitations and costs around $34.95 for the home edition.

If you don't want to use this plugin, Windows Media Player alone cannot trim MP3 files, and you may have to use dedicated audio trimmer software or online tools for trimming MP3s.