Alright, so I just got my iMac back from the store and I login to it knowing my password was correct, later I was trying to download a JDK but a window pop up asking me for the password of the admin account. I proceeded to entered my password but it won't accept it, all it does is say that it's wrong although I typed the exact same password. I tried contacting many people that I know but it still isn't working. Is there anyone who can identify this problem for me? If so then please do tell me how to fix it.
Password not working (it said the password I typed in was wrong)
password
Related Solutions
If you see the old unlock screen (gray window asking for your username and password) you have to delete the following file:
/etc/cacloginconfig.plist
If you delete this file, you will see the new unlock screen (like the login screen) and touch ID will work again.
Summary: If "/etc/cacloginconfig.plist" exists in 10.9 +, the screensaver unlock screen will be controlled by SecurityAgent (old style). Admins, when they successfully authenticate, will be allowed to take over the user's session. Even if "system.login.screensaver" in AuthDB is set to "use-login-window-ui", this will be overridden by the existence of "/etc/cacloginconfig.plist". We will still be presented with the SecurityAgent style login window.
More Info: http://www.openradar.me/19177988
Same problem here. Read and on and I'll tell you what I did to solve this problem:
I do Time Machine to an encrypted external Hard Disk. I stored the password to the disk in the default Keychain, and the system mounted the disk automatically after plugging it in. But suddenly, last morning, after I plugged in the disk, it prompted me for a password (it never did, since it was set to remember the password). In that dialogue, type a wrong password and the dialog does the wrong-password, shake animation, and it prompts for a password again; but type the correct password and the dialog freezes, like this: 
The solution I have found to work is as follows:
- Launch Disk Utility and Select the Drive that won't unlock.
- Click on Verify Disk (after it finished it told me the disk needed repair), and after it finishes with the verification, click Repair Disk.
- I let the computer do it's job, and after a while (about 30 min), it told me the disk couldn't be repaired, but the disk was now mounted, and working normally. Like shown in the following screenshot:
And now, my Time Machine drive works normally again:
So, launch Disk Utility, then Verify and Repair your faulty disk as needed. This worked in my case.
Best Answer
It has been a while since I have tried this so I assume it still works
Press the power button while holding down Command-R. The Mac will boot into Recovery mode.
Select Disk Utility and press Continue.
Or you could google "reset mac password" and follow the instructions I found and pasted in above.