More reads on sync and it's process.

https://support.mozilla.org/en-US/kb/how-do-i-set-sync-my-computer https://support.mozilla.org/en-US/products/firefox/sync https://support.mozilla.org/en-US/products/firefox/sync-and-save https://support.mozilla.org/bm/products/firefox/sync-and-save

You'll want to readup what sync can and can't do here for the FAQ.

I am really sorry that I use Firefox. I have not been able to access my bookmarks for 3 days and there is no solution for this. All my plans are messed up, I'm really sorry for myself and Firefox

I'm sorry to hear about the trouble you're facing with your Firefox history and bookmarks after reinstalling Windows. Let's see if we can help you get them back! First, please ensure you are signed in to your Firefox account in the new Windows installation. Then, go to the Firefox menu and click on "Sync Now" to sync your data. If that doesn't work, you can try going to the "Library" menu and selecting "Restore" to see if your bookmarks and history are available for restoration. If you still can't find them, don't worry, we'll do our best to assist you in the Firefox Support Forum. We're here to support you, and together, we'll get your bookmarks and history back on track. Hang in there, we've got your back!

Unfortunately, your solution did not work either.