Wifi connection issues Yesterday, we changed the service provider of the office wi-fi and since then, my Samsung Galaxy Tab3 (8.0) working with Android 4.2.2, has stopped recognising my office wi-fi. 

It is working well on other wi-fi connections. My cell, my laptop recognise the office wi-fi but its my Tab that refuses to play ball.

Could someone help me out here ?
Try powering down the device.  Turn it all the way off, not just reset.  This will ensure power cycling the NIC.

When you power it off, make sure it's off for at least 30 seconds.