Restoring a backup of MyPlaza not working

[ZiNgA BuRgA]

There were a few bugs found in an older version of the backup system.

If, all you need is for MyPlaza to be able to work with multiple themes, edit /inc/myplaza/myplaza_install.php and change the MYBB_REPLACE_TEMPLATES part, from the number '1' to '-1'.
Make sure you deactivate MyPlaza before doing this!

As for restoring backups, I can't really do much, unfortunately, if you've used an older version to perform the backup, as it may be stuffed.
You can always perform a database backup instead...

Hope that helps.