My wifi works on my handheld devices but ever since my laptop fell the wifi hasn't been working and i wanted to know how to fix it thank you.

As I'm sure you know, when you drop a laptop rarely does any good come from it. That said, You may have jarred lose a connection, or component, the antenna is sometimes located behing the monitor. I don't know your skill level, or if you are comfortable with opening the laptop to search for a lose connection/component. If no, take it to a Qualified Computer Tech. It's difficult to say what the problen is without opening the case. This may help, MIND those tiny screws, DON'T FORGET TO REMOVE AC AND BATTERY , and ESD protection: http://support.dell.com/support/edocs/systems/lat2120/en/SM/parts.htm

It would be good if you could post the make and model and version of windows. Without that, turn the the laptop upside down and there are doors or hatches on the bottom, they might have screws. Remove them and look for a small card with electronics on it. The card should be almost square in shape (not long rectangles) Make sure that it is not loose. It either pushes in or slides into a slot. If it slides into a slot you may have to remove it and put it back. It slides in at and angle and then presses down towards the computer and there are little clips on the edge that hold it.