IPhone 4s fell and Wi-Fi isn't working anymore?

Yesterday my iPhone fell from my pocket when I jumped (stupid I know) and it hit the floor with its upper left corner near the camera. Everything's fine, including the camera, but Wi-Fi isn't working anymore. It isn't greyed out, but it only detects a network when I'm standing 2 cm away from the router literally. I'm running out of cellular data so I will need to use Wi-Fi soon if I don't want to be charged a lot. I suppose it's the fact that when my phone fell, the Wi-Fi antenna kind of misplaced or moved or something so I just need to adjust it back again but I need to know how to do that. Anyways, I'm not sure but I don't have any money at the moment, so I would like to know if there's any way to do it at home without messing my iPhone of course.

Call apple