Hi, you do not mention a 2nd device from which you could recover the data from as Sync is for connecting devices (plural). It appears from your question, that you are using Firefox Sync as a back up service. This is not what Sync is designed to do. The Firefox Sync service takes a copy of the data you wish to include and transfers it to a second device (typically a mobile device such as a tablet or a telephone) running a copy of Firefox. The storage in between all attached devices is both temporary and fragile and is not stable enough to be (and is not designed as) a reliable backup service.

If you have a copy of your Firefox profile for desktop Firefox, you may be able to recover your bookmarks and other data. Please have a read of these article.

• https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles
• https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer

If you have a copy of your data on a mobile version of Firefox, please follow these instructions to connect it to Firefox Sync to copy your data.

• https://support.mozilla.org/en-US/kb/how-do-i-set-sync-my-computer#w_connect-additional-devices-to-sync_

Please let us know if this solved your issue or if need further assistance.

Thanks for the reply :) I visited these links, but that didn't seem to help. I have no problem with bookmarks, tabs, only with history of visited pages. I wonder if the history is automatically deleted after a certain period of time after visiting website? Heh, I thought that sync would keep my history so I didn't looked up for any other way to make backup. I'm not sure if I had made sync on my old PC. When I have access to it, I will check it. I'm afraid that I don't have any backup made in 'Library' (it make backup of all files with history, not only bookmarks?)