If you have ownership of the account associated with this system, then it will be possible for you to change the dealer of record. What this does is enables another dealer to have login access remotely, not just on site, and changes / updates can be made. If you don't have a login access, try to contact your real estate agent, lawyer or previous owner to have the email address and password given to you. You can change the email and password to your preferences.
If the previous network equipment was removed, or you installed your own, that may explain why the system is not working or broken. It won't be possible for a dealer to connect remotely either until the primary controller is "network reset".
I offer remote programming services, as well as on site. I don't change anything to have a look.
Send me a private message if you're able to log into the control4 account associated with this system. I may be able to assist you with the equipment you have if you can send or post pictures.