Boot into Recovery mode: F11 while booting or Boot CD/USB
The following screens appear one after another, after following your vendor's method of entering into recovery mode.
(http://s2.postimg.org/ns92f8a0l/keyboard_layout.jpg) (http://postimg.org/image/ns92f8a0l/)
Choose your keyboard layout.
(http://s1.postimg.org/wdla2aocr/Choose_Option.jpg) (http://postimg.org/image/wdla2aocr/)
Choose !!!!!****Troubleshooting!!!!***** option
(http://s4.postimg.org/vo2lubyd5/Trouble_Shoot.jpg) (http://postimg.org/image/vo2lubyd5/)
Choose Advance option..
(http://s23.postimg.org/cteytmiif/Advanced.jpg) (http://postimg.org/image/cteytmiif/)
Choose Command Prompt option.
rename utilman.exe utilman2.exe
rename cmd.exe utilman.exe
Now restart your computer, at the logon screen, click on bottom left icon and command prompt will open. Now use the net user trick
(http://s22.postimg.org/6vhbokkst/reset_password.jpg) (http://postimg.org/image/6vhbokkst/)
Open CMD (command prompt) with administrative rights to type this command.
net user <user-name> <Password>
Reboot, after getting into Windows 8, please remember to rename the Utilman.exe.bak back to Utilman.exe.
That's it – you have successfully reset your forgotten Windows 8 password.