So I had just gotten windows 10, I was using it fine, Cortana could hear me perfectly well, then my little brother came up and pressed a bunch of random keys on the keyboard. Ever since then, Cortana could not hear anything I'm saying, and I don't know how to fix it.

Set Cortana  to hear you anytime you say "Hey Cortana." Select the search box on the taskbar to open Cortana    home. Then select Notebook > Settings  and turn on Let Cortana    respond when you say "Hey Cortana."

Hi,

How about your problem now? How about disable Cortana and re-enable it for test to fix this problem? Please have a try.