wHATS THE defaut password ?

There is no default password. It's whatever you set it to be when you first setup the mac. What operating system are you running? If you forgot the password and you have an install disk, you can boot to it and use terminal to reset the password. You open terminal in utilities on the install disk and type reset password and hit inter. That takes you to a password reset screen. If you do not have the disk, you will need to use single user to do this. http://osxdaily.com/2011/04/25/change-admin-password-mac/

If this is your Mac and you set it up nobody else knows your password.

Which password is it, user, firmware, account, something else.

And start answering questions now, is this your Mac, was it new when you got it, when you answer them I may be able to help.

Then take your Mac to an Apple Store and ask them. There is no default password, there is no default account, if you had set the Mac up you would know that.

I can not be sure that this is your Mac so will leave now.