Sorry about the trouble caused as you cannot locate the restored library from Photoshop.
Which version of Photoshop CC are you using? From what I understand, have you followed the same procedure to restore the library assets as mentioned below?
You get a small warning for a few seconds after you delete a item that lets you undo. If you need to undo something later, you can go to the web interface for synced assets, go to Libraries > Archived to restore deleted items: Adobe Creative Cloud
There is no warning for a full libary. One "you sure?" and then *PERMANENTLY* deletes an entire library of files. How has this gone unsolved? You provide an undo for individual files, but potentially massive sets are gone permanently? Please fix this. This is bananas, guys.