Root Account Deleted

Hi, I have been assigned a small task by copying the configuration "UCS files" from F5 platform to another(3900 to 2000S). Hhmmmmmm easy right? Ok? Everthing went fine except for the Root Account. This Root account, for strange unknown reason on the old device,has been deleted where i cannot see it in the configuration utility(System->Platform). This problem also been replicated/copied to the new device. So, I cannot access the Root via CLI remote access or console on the new device.

I tried to reset the root password from the tmsh "using the admin account" but still i cannot access CLI, i also tried to add the "Root" as a username but i faced an issue "username already exist" or something like that.

Does anybody have any idea what could be the issue or how to fix this???

Regards, George