Sorry - no recovery is possible unless you made a backup.

When you load a user file it replaces whatever user objects existed.

This doesn't help you recover anything - but it's important to do frequent backups to avoid losing your work.   When creating a backup file, I would not only keep it stored on the USB flash drive but also copy it to a computer and send an email attachment to myself so it's backed up in 3 places (USB stick, Computer Hard Drive, Email).  If you have a fire and lose your keyboard/computer - insurance may get you new devices but your data would be lost.  That's what the email is for -- putting one backup "in the cloud".

If you're loading anything - that's a good time to ask yourself if you should create another backup.   Loading content (other user/library files) or updating your firmware.   If you've added a lot of Performances since the last backup it's probably a good time to make another backup.

I've had to start over a few times -- it's no fun.  Hang in there.  

You may want to request a feature inspired from this (ideascale).   Something along the lines of asking if you want to backup the user area to the USB stick before loading a user file or confirm you want to overwrite the user area with the user file.   There's probably a way to make it more clear what's going to happen.  I can't remember if there's already a warning or not.