Network problem and all app automatically closed please solve issues

Hi manjinder225,

Welcome to the Apple Community, where somer of us do our best to help each other :)

Apple support have an article online to help you:

If your iPhone, iPad, or iPod touch won’t connect to a Wi-Fi network

https://support.apple.com/en-us/HT204051

Or

You might want to try other links in this discussion thread:

If iPhone network is "locked ?"

https://discussions.apple.com/thread/252878708

Hope this helps :)