@fnkysid there are just to many possibilities to give you a concrete answer. The very first thing you want to do is to go through the Samsung [https://www.samsung.com/in/support/mobile-devices/how-to-troubleshoot-a-galaxy-phone-that-wont-connect-to-a-wi-fi-network/|troubleshooting site] Follow those directions first.
If none of that is working, then there is a possibility that you are having issues with the WiFi antenna or the WiFi/BT IC on your mainboard. For that follow the troubleshooting flowchart
[image|3388593]
Measure the voltages according to the flowchart. To identify the location of these components on the circuit board, use the [document|39171] and do a search with your PDF reader for the listed number i.e. C3012 and so on.