Didn't eject my external hard drive now it will not reconnect
I just got my MacBook Air, been using a PC up until now. Earlier this morning I plugged in my external hard drive and transfered some music onto my MacBook Air. When I removed my external hard drive I didn't not eject it, now when I plug it in my MacBook does not even see it. I tried different hard drives and I can see them. I even tried using that hard drive on my old PC and it works. How do I get my MacBook to recognize the hard drive again? Still new to the whole MacBook experience.
MacBook Air, OS X Mountain Lion (10.8.2)