My phone is a Lumia 535 with single sim and any sim if we put its not showing signal and not working, what do I do?

[Windows Central Question]

my phn is lumia 535 with single sim and any sim if we put its not showing signal and not working

my phn is lumia 535 with single sim and any sim and just i can use app flexibility but without sim how can i connect to people...help me wat to do