Hi, you can try this: First open bookmarks > Show All Bookmarks > Import and Backup > Restore, and see if you have a backup there. If not, please see- *[[Profiles - Where Firefox stores your bookmarks, passwords and other user data]]. *[[Recovering important data from an old profile]]. If your question is resolved by this or another answer, please take a minute to let us know. Thank you.

As you did a restore, did this leave your previous data in a file somewhere? Check the instructions of the program that did the work.