Open System Settings --> Wireless & Networks -- >> WiFi connection, touch on the Wi-Fi network that you’re unable to connect and select option “Forget.” after that try to reconnect
'''Step 02'''
Open System Settings --> Wireless & Networks --> WiFi Connection, press Menu button and select Advanced----> select WiFi Frequency
Check with Auto mode and try to connect with 2.4Ghz band.
'''Step 03'''
Backup all data and Reset the phone. after resetting phone try to connect with WiFi
irfan sanam,
'''Step 01 '''
Open System Settings --> Wireless & Networks -- >> WiFi connection, touch on the Wi-Fi network that you’re unable to connect and select option “Forget.” after that try to reconnect
'''Step 02'''
Open System Settings --> Wireless & Networks --> WiFi Connection, press Menu button and select Advanced----> select WiFi Frequency
Check with Auto mode and try to connect with 2.4Ghz band.
'''Step 03'''
Backup all data and Reset the phone. after resetting phone try to connect with WiFi