1 T Seagate Free Agent Go hard drive

I don't know much about seagate, but I've had several Western Digital MyBooks and have run into problems after dropping the drive twice. Based on what you're describing there has been some definite damage done, but it might not be to the drive itself. If it is the drive that's damaged then there's nothing you can do (at least not in your home). If it's not the drive then there is an option that I've had some success with. However it is risky, it will void your warranty, and it may damage your drive.

The MyBook external hard drives are really just regular internal hard drives with a fancy enclosure, as are most 'external' hard drivers. If you can get the casing off then you can either mount it inside of your case or use an external SATA cable. Sounds simple enough, but those casing are a bear to get apart - you're going to have to pry it open carefully with screwdrivers and pliers which makes it dangerous. Also, like I said, it won't help if the drive itself is damaged, but if the cheap SATA to USB controller is the only thing damaged, then you'll save your data.

The pry-it-open-with-force option should almost always be the last option and this case is no exception, but when you're at the stage where you can't read the drive, the lights aren't functioning properly, and the OS is having trouble with the drivers, one thing that will not work is the unplug-and-replug approach.