Computer WIFI not there?!?

I have a dell computer, and it crashed a few weeks ago, i finally got it going again by restarting EVERYTHING fresh and reinstalling windows so everything was wiped out.... now i dont have WIFI. only blue tooth... so i cant get internet on the thing. i've tried a few things to get WIFI installed on the laptop so i can use it, but nothing has worked...anyone have any recomnendations i can use???