Q: Why can not connecting to the wifi ? And how to solve the problem i have to make ?

Hi JasmineZeng,

From your post I understand that your iPhone is unable to connect to either a single Wi-Fi network or multiple Wi-Fi networks, and you are trying to update it to iOS 8.3.  As a first step of troubleshooting the issue of being unable to connect to Wi-Fi, I suggest updating your iPhone to the latest iOS version, 8.3, by connecting the iPhone to iTunes on your computer and updating.  If you'd like to follow the directions for doing this, please select the link below.

Update your device using iTunes

If you can’t update wirelessly, or if you want to update with iTunes, follow these steps:

1. Install the latest version of iTuneson your computer.
2. Plug in your device to your computer.
3. In iTunes, select your device.
4. In the Summary pane, click Check for Update. 
   
5. Click Download and Update.

If you don't have enough free space to update using iTunes, you'll need todelete content manuallyfrom your device.

Find out what to doif you get other error messages while updating your device.

Update the iOS software on your iPhone, iPad, and iPod touch - Apple Support

Cheers,

Alex H.