Iphone 4 won't let me use my 3G?

I have had my iPhone 4 for a while now and it has worked perfect. However a few days ago my 3G stopped Woking it say it's on and the 3G comes up in the corner of the phone but it doesn't work. Also when I try to turn some of the apps of so it won't connected to the 3G they turn them selves back on again, but when I go to use the app with my 3G it says My 3G turned of. Any suggestions or solutions to what could be wrong and how I can fix it?

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  • Windows Movie Maker won't let me use a video I recorded with my iPhone 4? Why not? I open Windows Movie Maker, and I browse through my pictures/videos and it's not there. Every video I have with my webcam is there, but none of my videos with my iPhone is there. And I don't want to upload the video straight from my iphone because I know the quality will end up being terrible. What do I do?
  • Why won't windows movie maker let me use my video? So i have videos from my iphone that i want to put on WMM, but it wouldnt let me because of the format. I installed a codec and converted it to AVI from. MOV and it won't let me look at the video, its just a black screen.
  • Why won't my iPhone let me use my email? I tried to add my email address to my new iPhone earlier. I put it my name, email address and password, but it says,'The username or password for pop3.live.com is incorrect.' (I have no idea what pop3.live.com is) My email address is correct because I have used it for years prior to today, and my password is correct because I checked it on my email on a computer recently and it worked! So why won't it work now?!
  • Virus won't let me use Internet? I'm connected to the internet but can't browse anything. I called Microsoft and did everything the told me. I also called my ISP and did everything they told me. They came to the conclusion that it's a virus but I don't understand how to fix it without the Internet. Please help. I'm using my iPhone on my home Wi-Fi to type this so I defiantly know it's not the Internet connection.