I never set up my smart TV as y et it it got stolen how can I find it

Everyone here is being negative about your question but if you had set up a Roku account for the TV it's not impossible (merely improbably) that it could be traced to an IP address if the thief attempted to use the Roku in the TV. I doubt you could prove to Roku that this set was yours or that they would take the trouble to help but it's not insane to think it could be done.
 

U are giving OP false hope.

What IP address? (I.T. guy here). The Roku sits behind a router getting a private IP hidden from public, this is not like a smartphone with a unique IMEI. In order to "find a laptop" software has be configured and enabled for tracing function, so it can "call home" and cannot be an after-thought like most people react after the heist.