I recently turned my iPhone off and then on. Once back on the service bars stayed grayed out. I tried making a phone call, it went through, and the bars came back on. However, I have had no cellular data (internet access) since restarting my phone. I can make calls and use the internet with wifi but texts go through very slowly and there is no internet with wifi off and cellular on. Is there a way to fix this or do I need to take my phone in for repair?