If your data was not backed up or on another device then there is nothing we can do.

My data had been syncronized all the time with that tool in firefox, I read the following post https://support.mozilla.org/en-US/questions/1400502 I hope exactly the same thing happens but I'm really scared to lose that information. That's why I was asking if it is not possible to check a version history of the sync tool to be sure which version I want to restore since with this new installation it seems to be syncing this newly installed version instead of restoring my data. Or maybe if there is another way. Thx!

As mentioned on clean install of OS and no backup of Firefox profile/bookmarks/session/history data to copy locally back - when you sync again it clears the sync data of the previous to current if it has nothing then sync data has nothing to save and anything before that was on the sync is gone now.