iPhone 6 connection problem, it says seeking or no coverage

I have an iphone6 and i have got problem to get my operator Telia a connection.

My phone just say seeking or no coverage. I was in contact with telia and they told me to

Reset network and i worked one time but nkw when i an döing tjat it doesnt help.

Can you help me with some suggestion id it is possible to get it to work again.

[Re-Titled by Moderator]