Dell Inspiron 15 unable to find network adapter

Hello, I use to have windows 8 on my laptop, but then my hard drive stopped working. I then bought a new hard drive and bought windows 7 and downloaded it onto my laptop. Everything is working besides the wifi. I've tried going into the computer management and going to device manager. I cannot find network adapter. All I see is other devices with Ethernet Controller, Network Controller, PCI Simple Communications Controller, SM bus controller, Universal serial bus controller, and USB2.0-CRW. All of those have a yellow exclamation point next to them. I cannot update or install them. Please help :)