first to check if the computer is connect to the router or not.

if you are using ethernet wire then you will have to reset the router by pushing the reset button on your router.wait for 15 to 30 mins.also reset your dsl modem which you have to do first before resetting router.this is under all drivers installed condition.while the modem and router is resetting shut down your laptop and start after like 30 mins.enjoy!