If you mean Thunderbird profile folder was deleted when you reinstalled/ recovered etc Windows OS and therefore all your address books in Thunderbird went missing..... Do you see a 'windows.old' folder on the desktop ? If yes, it may contain the profile. Assuming it was in the default location, look in 'windows.old' folder for this location: * C:\Users\<Windows user name>\AppData\Roaming\Thunderbird\Profiles\<Profile name>\ In the 'profile name' folder there will two address book files that can be copy pasted into your current profile overwritting the current empty address books. They are called 'abook.mab' and 'history.mab'. These are the 'Personal Address Book' and 'Collected Addresses' address books. Must exit Thunderbird before you do this.