Oracle root Password Recovery

Press F2 at startup

A GRUB screen will display
Hit letter 'e' in keyboard
Using the arrow keys, move the cursor to the line for kernel
Hit letter 'e' in keyboard again.
You will see a command line After the last word/character append a space and the word 'single' (single mode)
Hit Enter.
Make sure the cursor is on the kernel line and Hit letter 'b' in keyboard it will boot machine in single user mode..

After system load into single mode,
Type  passwd
Enter new password and conform .
Then type exit. It will reboot the system.

:)