Try Audacity for format conversion. Free, open-source, wonderful audio editor. It supports quite a few file types, and with installation of some additional codecs, even more. Very good on-line help documentation. Windows, Mac, Linux
http://www.audacityteam.org/download/
PortableApps makes a dandy portable version for Windows, run it from a thumb-drive!
https://portableapps.com/apps/music_...acity_portable