I FOUND A HACK Y'ALL
http://archive.org/web/
This is the Wayback Machine. It's kinda like the Google Street View for websites.
You can use this to recover copies of old sets, collections, groups and comments.
Type in POLYVOREUSERNAME.polyvore.com in the text box and see what comes up. This is not perfect; depending on what tab you click you may end up with different versions of your profile from different years.
Google Cache is also another method.
https://webcache.googleusercontent.com/search?q=cache:jajb73hOF6EJ:https://princess70xox.polyvore.com/+&cd=5&hl=en&ct=clnk&gl=us
Try it with your profile!