To judge the problem and how to deal with it:
First, if your iphone5 can't connect to the computer, you can connect to a friend's computer.
1. If your iphone is still not connected and his iphone5 can be used properly, it means your phone is out of the question. Solution: Backup the data to the icloud, then brush the machine, restore the factory value.
2. If your mobile phone can connect to each other's computer, and not even their own computer, indicating that your computer has problems (the same data line). Solution: Check whether the computer's USB drive is installed, the port is turned off, or switch to a USB jack.
Second, if you can connect to the computer, but not even itunes, you first try to connect to the friend of the computer itunes (do not have to bind, see whether can detect on the line).
1. If its itunes detects his iphone, but does not detect your iphone, your iphone5 still has an unknown problem. Solution: Still need network backup, restore factory value or brush machine.
2. If its itunes detects your iphone, it means there is something wrong with your itunes program. Workaround: Make sure itunes system services are open and reinstall itunes if you don't understand it.