After a hard power off, Windows entered in a loop: Preparing Automatic Repair, and then opens a blue screen.

All my data, my folders, etc are there, but windows refuses to boot.

Tried Refresh
Tried:
bootrec /fixMBR
bootrec /Fixboot
bootrec /rebuildBCD

and also
chkdsk /r c:
Got nothing until now....

DELL's support says to do a FULL RESTORE, but this is my LAST option, please, there should be a way to reinstall or repair windows8 only, and not touch my data.

What information is on the bluescreen? Is there a Bug_Check or Stop Code?

You may have done part of this however please do these as listed below.

How to Create a Bootable USB or DVD with a Windows 8 ISO http://www.eightforums.com/tutorials/2227-create-bootable-usb-dvd-windows-8-iso.html

You can try this if you can create a System Repair Disc on another Windows 8 computer.
Must have the same version of Windows 8 - 32 or 64 bit.
How to Create a "System Repair Disc" (CD/DVD) in Windows 8 (see Related Tutorial section as needed)

http://www.eightforums.com/tutorials/2855-system-repair-disc-create-windows-8-a.html

Note using Win Key + X and Win Key + W (to get to Control Panel, Run, and Settings as needed). Win Key + D calls the desktop and the using Win Key toggles Desktop and Start Screen.

Translate the Windows 7 methods to Windows 8.

Boot with a Installation or Repair disc or USB drive - issue these from the Command Prompt and hit ENTER after each.
C:
bootrec /fixmbr
bootrec /fixboot
bootrec /scanos
bootrec /rebuildbcd

After the above you may need to run Automatic Repair (even 2 or 3 times)

http://www.eightforums.com/tutorials/2843-automatic-repair-run-windows-8-a.html