Well, you still have the Linux option to try, in order to find out if it can access the drive so that you can recover your files and then reformat it. Other than that, this could be due to a virus, so I'd recommend that you have an anti-virus program up and running (with an updated database) when you connect the drive. Try to see if you're able to scan it.
About the chkdsk command, this could potentially be data destructive so you should avoid it unless you have no other options left to exploit. Here's how to try and tun it in offline mode: type chkdsk E: /scan /forceofflinefix this will queu the drive for offline repair, this way it might be able to scan it.