What happened to my network locator?

At first my phone's ( Lumia 925) screen (LCD) cracked and the crack subsequently disabled every form of sensitivity on the touch screen... I than replaced the cracked screen at a cellphone repair shop, now my phone is working again but it seems to fail in locating my current network provider (MTN).

Technicians believe its a hardware issue and not so much so a software problem.

Whenever I insert my sim card (or any other sim card for that reason) it simply reflect "no network found"

How do I get this fixed?