Iphone 7 pus coverage experied

For your cellular access contact your carrier.

For your coverage (assuming you mean AppleCare+) see:About continuing your AppleCare+ coverage for iPhone, iPad, and Apple Watch - Apple Support. Note you can only extend the AppleCare+ if you purchased it when you got the phone. You cannot extend the 1 year warranty if it has expired.

"No service" and "network not avaialble" would be something you'll need to take up with your cell carrier.

As to "coverage expired", that depends on where you're seeing that, but it may be saying that your warranty and service coverage with Apple has expired, which for an iPhone 7 happened long ago. If that's the case, though, the screen should have much more information about your service and support with Apple. If that's not what you're seeing, then again, you need to contact your cell carriers.

Regards.