Is this the culprit?

Okay so i tried a self repair on my iphone 4s. i replaced the screen and everything is fine. when i turned it back on,it keeps saying No service. Wifi is fine, and so is bluetooth.

when i opened it back i noticed that component in the yellow box is missing. so

1. could that be the source of my problem?

2. if yes, would soldering it back in (cause i still have it) fix the problem?

3. are there any other solutions besides soldering it in

4. does the component in the green box beside it have anything to do with my problem?

Thanks!