Ok... if it IS Dell Diagnostics, the Electronics are failing in the Hard Drive.
I can assist in getting your data back, however, CR / the Internet is like an asshole. Everyone thinks their's is the best.
Let me know via a PM if you would like my assistance. I will need your Hard Drive for a day or two, and will be able to recover all that anyone else here can. If I cannot get it, no one else here can offer anything that could.
KillJoy