hi andybyc, if you are referring to a recovery key this means you were using sync 1.1 ("old sync"). mozilla has shutdown and decommissioned its old sync infrastructure and servers end of september - this was communicated in product and by announcement at https://blog.mozilla.org/services/2015/07/31/shutting-down-the-legacy-sync-service/ old sync data will be gone if you have not upgraded to new sync in time unfortunately!

But what if try to install old version of FF ? maybe it will help ?

Not now - that may have worked before the old 1.1 version Sync servers were shut down on Sept 30th, as philipp mentioned.

Overall, neither version of Sync is / was intended to be used in that manner - as a backup medium or 'cloud' service. Sync is for "synchronizing" Firefox data among multiple devices, where at least one device would always have your data when another was sent out for service or reformatted.

See also:

• https://support.mozilla.org/kb/restore-bookmarks-from-backup-or-move-them
• https://support.mozilla.org/kb/Backing+up+your+information

yeah, my case was very difficult, bezause i was 1 month without pc, and it was that month, in which servers was disabled.

have you ever tried to contact with persons responsible for maintenance ? some mails, infoline, etc. ?