Hey guys, so this is my story.
Some days ago my PC started having some serious performance issues, whenever i did something that needed resources it would hang for some seconds (10-15?) and then continue.
At that point i wasn't sure about what is going on cause i never had those issues before and everything on the first look seemed normal, having no Antivirus i was thinking about a virus but im really cautious of how i use the internet and stuff

(i have to say at this point no weird noises from the drive , i have my PC right on my side and it has no lids so i would've heard it i guess)
So the other day i was backing up some cubase projects and it was doing the same thing hang but then did the job, so i was ready for a format ... but then and right before the last hang i get BSOD ! I try to restart but says :NO BOOT DRIVE (well , that kindof message).
At that point i understood that the HDD was behind those hangs.
So i take it to my other PC plug it in in various ways but none of them made it visible to even BIOS it's like its flushed nothing that says hey there's a drive pluged in that port but i can't open it / it's broken, nothing! ( not to even mention the disk repairing programs..) so i plug it in my external HD case and put my ear on it to hear what's goin on , to see if i have to fix maybe a stuck needle , do the fast copy of the folder i need and then throw it in the trash)
But, nothing of course.
The sound was like it wanted to start but couldn't and then dead, no sound whatsoever, i opened him up to see if i understand anything but everything seemed fine...
Disk model : WD6400AAVS 640GB , running windows 7 with 2 partitions.
So, guys any ideas / ways i can repair this problem ? Or how the problem was caused?!
Any help is much appreciated
Thank you for your time!!