Yes and no, all a program will do is make a bigger file. Unfortunatly when an MP3 is encoded at a low rate you can't get back what is lost, it's like cutting a piece of paper in half, throwing one half away and trying to turn it back into a full sheet of paper.
I have not tried this program -> http://www.nesoft.org/wav_mp3_wma_converter.shtml and you may be running a Macintosh.
Does anyone know how to change the bitrate of an MP3? It is currently at 11k and I would like it to be 48k. I have tried several programs unsuccessfully. Thanks in advance for any help.