I have a macbook pro, stuck in grey screen, when I press option key to reboot ask me for password, is any idea or other way to reboot this computer ?
Its possible that you have a firmware password on your computer that is preventing you from using the "option" boot key. This key allows you to boot from other volumes on your drive. If you need this reset, I recommend going to an Apple Service Location.
As for the grey screen, you will have to be more specific.
If you see the apple logo, but doesn't boot, its probably an operating system issue.
If you don't see anything, its possibly a bad Hard Drive, or Hard Drive Flex Cable, and its not recognizing your hardware.
To test this, you can boot from your "disk 1" cd, then goto "Utilities" at the top of the screen, then goto "Disk Utility". If you hard drive doesn't come up, then its probably a dead hard drive or flex cable. If it does show up, goto "First Aid" and run a "Repair Disk" and see if it will repair it. Be warned however that if your hard drive is indeed failing, trying to access its contents, or repair them will damage your data further and making it harder to recover.