Welcome to Justanswer.com, my name is Dustin.I'm sorry to hear about the issue you are having, I will do my best to help you resolve it.
So I can help you, we need some basic info..
Is it an ipad or iphone that was stolen?
Or, was it a Samsung Note 4 or Galaxy S7 ? We have to have an idea of the type of device that went missing, if we are going to use any possible tools available to lock or shut down the phone.
Thank you for your response,
Understood.. Who is your phone service with?: