External Drive no longer working

Hi, I have a Toshiba 1tb external drive that I've been using just fine until today. I got a new iPod and was loading music on and needed to set it back to factory settings from iTunes. After I did this, the external drive is no longer being seen by my macbook pro. I checked in system profiler and it's showing there, but it won't show in finder and I can't access it. Any ideas? If anything is there any way to recover the information from the drive? Thanks for any help!