Você precisará redefinir sua conta do Firefox Sync e adicionar todos os dispositivos novamente :
At the top of the Firefox window, click on the Firefox button (Tools menu in Windows XP) and then click Options Once the options window opens, click on the Sync tab. In the Sync tab click on Manage Account and select My Recovery Key. A new window will open displaying a Recovery Key - ignore that and click Generate a new key. A new Recovery Key will be made for you. Please take a moment to print it out or save it on your computer. Then click Change Recovery Key
You should see two status messages. The first one will say, "Changing Recovery Key and uploading local data, please wait..." and the second one will say, "Your Recovery Key was successfully changed!". Once your Recovery Key has been changed the window will close. Note: This first sync should happen quickly but may take more than 30 minutes, depending on how much information needs to be synced. Click OK to close the Options window
Now that you've changed your Recovery Key, any devices you had connected to your Sync account will stop syncing. You'll have to re-add them to your Sync account by following the steps in How to sync Firefox settings between computers or How do I sync Firefox between my desktop and mobile?.