Hey there, IamReact!
Unfortunately, @Supermuncher85 is right, the HDD has failed - that what the Disk Self Test (DST) usually indicates.
I'd recommend you to contact your computer/laptop manufacturer if it's still under warranty, their customer support should take care of the HDD replacement. If not, you should start looking for a replacement yourself.
Good luck! Hope we were helpful!
SuperSoph_WD