Hi

Thank you for your question about the Firefox Sync service.

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 this article.

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.

Yes, but last time I reinstalled my computer (SO, etc), firefox sync detected all my bookmarks, etc. Now it don't. Why? Thank you

When you reset your Sync password all your data is wiped from the Sync server.

Two reasons for that action: 1. It's a maintenance feature - to clear corrupted data so the user doesn't need to create a new account (using a different email address) to fix corrupt Sync data after fixing the Places databases in multiple Firefox installations. 2. The password is used to create the dual encryption keys that Sync uses to encrypt and decrypt user data when that data is "off" the connected devices; IOW during the "trip" to the Sync server and while the user's data is on the Sync server. Only the user ever see's the account password and the dual "keys" - Mozilla never has access to that information, thus can't decrypt the data.

I would like to know if I you can look for all the IP which have been conected to my sync between 20 and 21 june.

Sorry, there is nothing that Mozilla can do to help you recover your data.

Changing the Sync password was a "fatal" action. So unless your data is still on the PC that wasn't "reinstalled", your data is gone.