This works but you should still stop and backup your ts3 server.
After you backup is complete follow these steps.
While ts3 server is stopped start the server using this command: (assuming you are running 64 bit server on windows)
(You can do this by making a shortcut and editing the target location as well)
Now you have an updated TS3 admin password, with this you can create a new privileged key.
Using puttytel.exe or any other telnet client to type the following commands:
(localhost if your server is hosted on the pc/server you are running telnet on, otherwise just use the ip or server name)
After the last command the server will respond with a token=YourNumbersAndLettersToeknID
Copy this and past it into your TS3 client under permissions > use privileged key.