I've lost my iPhone and the password for my Apple ID has been changed. Help me find my lost iPhone !

I've lost my iPhone . For the 2 factor aunthetication they've changed the trusted phone no. I've got the email as such that the trusted phone no is changed . I tried to locate to my iPhone from find my iPhone but it is disabled I have also got a mail regarding this .So how can I recover my phone o find my iphone ? With all these consequences how can I locate my iPhone?With a serious note the person seems to be having a high knowledge about iPhone

Please help me out resolving this issue as the customer support is not responding to my calls! Please do consider the Issue personally