I Was Making A Song And Renoise Crashed

Does renoise backup the file, and if so what folder does it go inot?

Yes, Renoise will try to make backups of the songs before it closes. You’ll find the backups in Renoise preference folders:

Windows XP: x:\Documents and Settings%username%\Application Data\Renoise%renoiseversion%
Windows Vista: x:\Users%username%\Application Data\Roaming\Renoise%renoiseversion%
MacOS: ~/Library/Logs/Renoise.log & ~/Library/Preferences/Renoise/%renoiseversion%
Linux: ~/.renoise/%renoiseversion%/

Could you please send me (taktik@renoise…) the log files from the prefereneces folder? Then we will try to find out how this could have happened.

you can also define backup properties into

Edit => Preferences => Misc

see also here