I have got a new laptop and wanted to transfer my all my Firefox browser including history, tabs, passwords, etc to my new laptop so It was my chance to try Firefox Sync. It has been a while since I transferred everything to my new laptop and format my old laptop and once I needed a website link from my Firefox bookmarks; I found all my bookmarks and general folders but NO sub folders and NO bookmarks inside the folders!
I’ve googled it and found Firefox Sync has some technical problems. Anyway the final solution to restore your Firefox bookmarks is:
1- Open Firefox
2- Show All Bookmarks
3- Click: Import and Backup
4- Restore -> then choose the date!
If you want to access this bookmarks file/folder go to your Firefox profile folder and you will find folder called “bookmarkbackups” and you can use this folder to copy and transfer your bookmarks between computers!