First, try looking for your Amiga Music MOD at one of these MOD resource websites:
Exotica has most if not all of what you need:
If you haven't found what you are looking for from above, try making a search on Google, always works. If nothing turns up, request it in Modules Requests Forum
Since they hold the mods mostly in their original, exotic formats, you will need Deliplayer to hear these tunes on your PC.
Alternative Players for Windows:
For Mac OS X, there's CocoModX, which will play SOME tunes (there's no decent Mac mod player :P)
And for the miggy, you have Eagleplayer and Delitracker
Player for linux: XMMS
And there's also UADE [Unix amiga Delitracker Emulator]
To convert tracker music modules to mp3/ogg/wav format you will need to use a program like winamp.
If you decide to use winamp’s Disk Writer Plugin to save the MOD as WAV then please make sure you have the Oldsk00l player plugin installed.
Download: Oldsk00l player for Winamp
Alternative methods include: