@saiasissahoo Open Device Manager and look for your WiFi adapter under Network Adapters. Does it have a yellow exclamation mark?
If so, that is a driver error. The driver needs reinstalling. Right click and hit Uninstall. Then reboot the computer.
If that still doesn't work, you may have a failing network adapter. As a cheap fix, you can buy a small usb WiFi dongle and leave it in the laptop.