My I have a Seagate 2TB USB3.0 External Hard Drive and it got dropped. Now it just wont connect. Its not clicking or anything it spinns up just fine and if you look at it in disk utility my computer clearly knows what it is, but the drive is coming up as unreadable or something.
@Devil240Z: sounds like something has happened to corrupt the filesystem, do a quick format of it and run a recovery utility on it. MY preference is www.runtime.org getdataback but that is just do to success with it for many years its quite possible there are better tools.
It COULD be that the connection between the power and the hdd is fucked. My brother-in-law had this happen to one of his external harddrives which he also dropped on the floor. Turned out that he could just take it out of the casing and put into a PC as an internal hdd and then it worked fine.
@Vetterli: Yeah if the HDD is fine you can take it out of casing and put it in your PC.
@Devil240Z: I would give what CrippleCap said a try. Sounds like the USB portion is working fine since you are saying it "recognizes" it.