Samsung mobile phones do not connect to the Internet.

The situation of my mobile phone is somewhat different from that of others. I couldn’t open the wireless network last year. I got the repair in the mobile phone shop and said that I have to spend a lot of money to fix it. After a year, I used my mobile phone to download offline novels and also played some stand-alone games. They are all connected with the computer 360 mobile assistant. Then just over a week ago. The phone suddenly opened the wireless network. After using it for a few days, the phone has a bit of a card. I think that the phone has a network, so there is no need to play stand-alone games and novels. Then I uninstalled the software under the computer. 360 mobile assistants, cleaning masters and the like are also unloaded. Then I can't open the network.

What's going on, how can I open the network again?

Addition: I remember that I used to find a way from the Internet, and what key is added to the power button. Come, I also opened the net, but after a few days it was closed again