How to fix No Service iPhone 4 problem?

I dropped my iPhone and I got it fixed. When I tried to connect to Wi-Fi it would not let me. The switch was dimmed. The bluetooth was also messed up. I then payed my phone bill, and it still showed no service. I know it's not my SIM card because when I put it into my sisters iPhone, it worked fine. I have AT&T. IOS 6.1.3, and my iPhone is a 4not a 4s. For some reason, after a while, the Wi-Fi started working, and it found networs but at around a weaker level. Bluetooth seems to be working fine also, but where I should have signal bars, I have No Service. I've already restored like 5 times, I also do not have insurance, so I do not know what to do.

Go to the iphone company