Replying to People who know shit about cars

Alright, so I let my buddy here at college borrow my car the other day just to go to Trader Joe's, which is less than 10 minutes away. It's been a couple days, and I haven't driven it since then. Tonight I went out to my car, and when I turned it on, the Emergency Brake light was on, but my Emergency Brake itself wasn't engaged or anything. Then, when I went to drive, I realized the brakes absoultely don't work at all until they're pressed to the ground, and even then it's a slow, jerky stop. So I'm fuckin pissed and freaking out at the same time here, and now I can't even get ahold of the guy. Does anyone know if there's anything he could have possibly done on such a small drive to do something like this, and what if anything I can do about it? I checked the brake fluid, and it looked full enough as far as I could tell, and I've been looking on the Internet and haven't found anything helpful. If anyone has any knowledge about this, that would be great.