Locked out of macbook air, won't accept password

You made the mistake of migrating the Guest account from the old system. That always causes problems. The best option would be to start over by erasing the startup volume in Recovery, reinstalling OS X, and then transferring the data again in Setup Assistant (not including the guest account.)

If you don't want to do that, see below.

If the user account is associated with an Apple ID, and you know the Apple ID password, then maybe theApple ID can be used to reset your user account password.

Otherwise*, boot into Recovery mode. When the OS X Utilities screen appears, select

Utilities ▹ Terminal

from the menu bar. In the window that opens, type this:

res

Press the tab key. The partial command you typed will automatically be completed to this:

resetpassword

Press return. A Reset Password window opens. Close the Terminal window to get it out of the way.

Select your boot volume ("Macintosh HD," unless you gave it a different name) if not already selected.

Select your username from the menu labeled Select the user account if not already selected.

Follow the prompts to reset the password. It's safest to choose a password that includes only the characters a-z, A-Z, and 0-9.

Select

 ▹ Restart

from the menu bar.

You should now be able to log in with the new password, but your Keychain will be reset (empty.) If you've forgotten the Keychain password (which is ordinarily the same as your login password), there's no way to recover it.

*Note: If you've activated FileVault, this procedure doesn't apply. Follow instead these instructions.

The first thing you should do with a second-hand computer is to erase the internal drive and install a clean copy of OS X. How you do that depends on the model. Look it up on this page to see what version was originally installed.

If the machine shipped with OS X 10.4 or 10.5, you need a boxed and shrink-wrapped retail Snow Leopard (OS X 10.6) installation disc, which you can get from the Apple Store or a reputable reseller — not from eBay or anything of the kind. If the machine has less than 1 GB of memory, you'll need to add more in order to install 10.6. I suggest you install as much memory as it can take, according to the technical specifications.

If the machine shipped with OS X 10.6, you need the installation media that came with it: gray installation discs, or a USB flash drive for some MacBook Air models. If you don't have the media, order replacements from Apple. A retail disc, or the gray discs from another model, will not work.

To boot from an optical disc or a flash drive, insert it, then reboot and hold down the C key at the startup chime. Release the key when you see the gray Apple logo on the screen.

If the machine shipped with OS X 10.7 or later, you don't need media. It should boot into Internet Recovery mode when you hold down the key combination option-command-R at the startup chime. Release the keys when you see a spinning globe.

Once booted from the disc or in Internet Recovery, launch Disk Utility and select the icon of the internal drive — not any of the volume icons nested beneath it. In the Partition tab, select the default options: a GUID partition table with one data volume in Mac OS Extended (Journaled) format. This operation will permanently remove all existing data on the drive, which is what you should do.

After partitioning, quit Disk Utility and run the OS X Installer. When the installation is done, the system will automatically reboot into the Setup Assistant, which will prompt you to transfer the data from another Mac, its backups, or from a Windows computer. If you have any data to transfer, this is usually the best time to do it.

You should then run Software Update and install all available system updates from Apple. If you want to upgrade to a major version of OS X newer than 10.6, get it from the Mac App Store. Note that you can't keep an upgraded version that was installed by the previous owner. He or she can't legally transfer it to you, and without the Apple ID you won't be able to update it in Software Update or reinstall, if that becomes necessary. The same goes for any App Store products that the previous owner installed — you have to repurchase them.

If the previous owner "accepted" the bundled iLife applications (iPhoto, iMovie, and Garage Band) in the App Store so that he or she could update them, then they're linked to that Apple ID and you won't be able to download them without buying them. Reportedly, Apple customer service has sometimes issued redemption codes for these apps to second owners who asked.

If the previous owner didn't deauthorize the computer in the iTunes Store under his Apple ID, you wont be able toauthorize it under your ID. In that case, contact iTunes Support.

So, it sounds like the next thing I need to do is find out what software it shipped with.

I explained how to do that in my last comment.

THANKYOU SO MUCH LINC! I CAN NOW USE MY MAC

Hi Linc,

perhaps you can help me too.

Bought a mac air - there is no disk with it. Worked fine, with my simple lock screen password. Then I changed password for my ID in iClaud. When I went to open my computer again, my previous screen lock password was not accepted (is the screen password the same on as in the iClaud, iTune, etc?)

Then i tried to put in the new iClaud password but it does not accept either.

So I am stack. I tried to reboot with command + S or R but nothing happens. I cannot switch it off beacuse it ask for the administrator ID (who is the administrator?) + a password. Again would the administrator password be the same as in the iClaud or is a different one?

hoe infurating!

tahnks if you can help

Hello, Linc,

I could not see how to start a new question, so forgive me for "interrupting" with a similar but different problem.

I have a 2011 MacBook Air, OS X 10.7.5 and have been very happy with it. Suddenly, though, when trying to approve installation of an Adobe update, I typed in my Admin password and it was rejected. I was given a hint, which fit the password I was inserting. I made sure caps lock was off and that I was using the correct keyboard. I never got a message saying use Apple ID to access this computer. It was continually rejected.

Then I tried the Users&Groups method to get in, but my only options there are Change Password (which I can't do because it doesn't take the password) or Change my Apple ID, open Address Book Card or Parental Controls.

Janet O'Donovan