Go to the wireless settings on your router and wifi signal broadcasting is on or off. if it is off please make it turn on.. then this will start working fine.
Thank you Mr. Phillip, I restarted the phone and the router, but it did not work. My phone is connecting to any other wifi automatically and also my all other colleagues have no problem with connecting to my office wifi.
Go to the wireless settings on your router and wifi signal broadcasting is on or off. if it is off please make it turn on.. then this will start working fine.