Audacity won't let me put MP3 on it

I don’t know what I did but for some reason Audacity will not let me out a MP3 file in it.

Sorry, are you saying you can’t open an MP3, or you can’t export-as MP3?

If you can’t open an MP3 (but you can play it with other software) try converting it to WAV with [u]Kabuu Audio Converter[/u]. Audacity decompress the MP3 (similar to a WAV file) when you open it anyway. (If you re-export as MP3 your new MP3 will be OK.)

…Audacity is more “picky” than most audio players about imperfect MP3s. If you’re using an older version of Audacity, you might try upgrading. There have been some changes related to this (some changes made it better and some made it worse).

We use LAME for Windows 3.99.3 which seems to export to MP3 without an issue.