You have a Xperia X compact and you don't have mobile network?
Maybe you can explain what steps you have taken.
Anyway, here are some hints.
The action not mentioned in this post is to take out both SIM and SD and restart.
Then shut down the device and just put in your SIM, or even better someone elses' SIM of which you know it functions well.
You might also call your provider and ask.
