How can I reset MBA password

Forgot Your Account Password

For Lion, Mountain Lion, or Mavericks

Boot to the Recovery HD:

Restart the computer and after the chime press and hold down the COMMAND and R keys until the menu screen appears. Alternatively, restart the computer and after the chime press and hold down the OPTION key until the boot manager screen appears. Select the Recovery HD and click on the downward pointing arrow button.

When the menubar appears select Terminal from the Utilities menu.

Enter resetpassword at the prompt and press RETURN. Follow

instructions in the dialog window that will appear.

Or see:

Reset a Mac OS X 10.7 Lion Password

OS X Mountain Lion- Reset a login password,

OS X Mavericks- Solve password problems,

OS X Lion- Apple ID can be used to reset your user account password.

For Snow Leopard and earlier with installer DVD

Mac OS X 10.6- If you forget your administrator password,

OS X- Changing or resetting an account password (Snow Leopard and earlier).

For Snow Leopard and earlier without installer DVD

How to reset your Mac OS X password without an installer disc | MacYourself

Reset OS X Password Without an OS X CD — Tech News and Analysis

How To Create A New Administrator Account - Hack Mac

If you encrypted the disk and can't remember the password then you have a problem unless you setup a recovery key.

I don't believe you have an operating system or working drive in your computer. From what year is your MBA? If it's a new model, then take it back to the store and let them sort things out for you. If it's not new then from the same Utilities menu select Disk Utility. Do you have a drive listed in the Disk Utility sidebar?

If your computer is using an encrypted disk and you don't know the password, then we can't help you.

It would appear you have no space left on your hard drive. No one knows your password but you. I don't see how we can help you when it is so unclear as to what your problem is.

In the reset password utility it should ask you to select the volume containing the User Account. If you click on that it should let you pick Macintosh HD like you see on the left in disk utility. Once you do that it should let you pick your user account.

Wow didnt see the snaps until after I posted a moment ago. Yeah you're boned. Into the Apple Store you go.

If you try to Erase the whole Hard Drive you could do it with Internet Recovery.

Need an internet connection.

Shut down computer.

Hold down Command + Option + R and Turn CPU back on.

Keep holding these til you see the spinning globe or Apple Logo or something that says starting Internet Recovery.

You can access Disk Utility there to Erase the whole drive then reinstall the OS fresh.

Select the top Line and choose Erase on the tabs to the right.

Make sure the format is Mac OS (Extended Journaled)

Name should be Macintosh HD by default.

Click erase on the bottom right.

The close Disk utility

Next choose reinstall

Select Macintosh HD as the location

Sit back and wait for it to finish.