Q: How to unautorize a PC?

Hi,

I need to have acces to my iTunes account through another computer. I suffer a robbery and I have changed my residence so I have a new equipment in which I wand to get acces to my music.... unfortunately I have not enough attempts to set my account in another PC.

How I can unauthorize the stolen computer and the old one that I used to use at my old job?

Sincerely,

Erick