Latitude E5420, Microphone Doesn't Work, Win 10

Hey guys,

We just upgraded our office of 50 people to Windows 10 from 7.  Pretty much the whole office it worked fine for, except my boss.  We can't get his microphone to work again and can't find the drivers on dell's website.  It's a Dell Latitude E5420.  I'm not sure if it's a Realtek internal speaker or what, but we've tried a few drivers on their site as well.  Any ideas would be great!

Thanks!