offline deactivation problem

Hello, 

I have tried to deactivate my license offline as I cannot have access to my old PC but unfortunately I could not. I have received this message every time I have used the deactivation ticket: An error has occurred with your offline-deactivation. If you continue to have problems, please Please log a support request.

I mention that I used this feature in the past and had no problem with it. 

Can you please tell me what to do to get my license back?

Thank you!