Think my external HD crashed...

Yep I have a three TB HD made by Seagate, model #- seagate 1dxap3-500, I usually leave it plugged in on my desktop machine, I noticed Istarted having problems when I went to import images in Lightroom and it is used for where I send my second backup location, I started getting messages that it couldnt save the images to that location.
so I decided to explore the HD and see if everything was still there, the main file menu is there but when I go to open any of the files it says each folder is empty, now when i try to open any folders the thing just hangs up, and I have to unplug it in order to get it to close.
I tried scanning it with Seagate software but get meessages like-too many errors or performance too low in the unit.
Is this a typical crash? will I even have a chance of retrieving my data? Any suggestions would be appreciated, I have had the HD for two years now.

ANY message prompted by accessing an HDD can be considered as ominous, could be getting ready to crash or has crashed. I would try to get the files onto another drive as soon as possible.

I have managed to get some of the files transferred, but it is hit and miss, I gotta keep connecting it and disconnecting it during the transfers, managed to get some important files moved, but now it isn't working at all.....