(I have a dell inspiron 15 3521 with a 5400 rpm hard drive that was also 500 gigs.)About a month ago my hard drive said have some errors then it noticeably slowed down. By taking 3+ minutes to shut down to when using it, it was like try to use the computer it was slow. So I ordered a new hard drive that was a 7200 rpm that was would fit my laptop and then I ordered a converter for 2.5 sata to usb which fit. Then I started easeUS todo backup and I was cloning my hard drive and it was about 65 percent done last time i checked then being 10 hours already then 5 hours later when I went to my computer it said please reinstall windows I guess because I left turn off computer once done on the easeus todo cloning and it rather did that or just went corrupt because when I pressed enter it said checking media [fail] checking media [fail] even this was the hard drive that I was using before that was working and my new hard drive had nothing on it. so I plugged up the new one to my old dell dimension and disk management said it was "Healthy GPT Protective Partition" and I cleaned it with diskpart in CMD on the windows xp computer and created a new partition so it would come up. The only thing I can think of doing is downloading windows 8.1 installer thingy and put that onto the disk but will that make my disk bootable to windows or do I have to do more? thanks and sorry for any bad grammar I am just really freaked out.