Well Sir there is a possibility that the wireless card may somehow be affected or have been damaged, I would suggest not to buy another internal wireless card unless you certain that the problem occur on the wireless card alone,  oneway to test is to try to look for someone you know a friend, or an officemates maybe who also using the same model of laptop or any Dell laptops who is using the same specifications as your wireless lan card, try to install  your wireless card onto it, if it works then the problem could be on your motherboard.