Welcome to the community!
Sorry to hear you've lost your phone. As I understand, you have a new phone and SIM with which you would like to use on your account. If that's the case, you will need to contact customer service to update your account with your new SIM card. The online Update SIM option would need the number of your old SIM card to proceed. Alternatively, you might consider sending @FidoSolutions a PM. Once they verify some information, they will also be able to access your account. In addition, they can also be contacted via Live Chat, Facebook, or Twitter. Those methods can be accessed via the contact page posted above.
Hope this helps 😀