Use this tag for issues with your device having locked you out and won't let you in anymore. See the full tag wiki for details and some first-aid hints.
What does "locked out" mean?
Android devices offer a lock screen to protect the device from
- being accidentally used while e.g. in the pocket
- being used by unauthorized people
You can read more about this in the lock-screens tag-wiki. Now, if you've used a PIN/password or pattern-lock to protect your device, and either forgotten it or (someone else) entered the wrong combination too many times, the device will lock you out. Even if you remember the correct combination, it might refuse to let you in and ask for additional steps to be taken.
Some first-aid available?
Sure. The full register of possibilities (as known at the time) is discussed in Can not unlock my Android device as have no internet connection? – so this is the first thing you should read before placing your own question.
Questions dealing with specific related issues
- Can not unlock my Android device as have no internet connection?
- How to unlock device when I forgot my password?
- How to unlock Google Device Manager remote lock?
similar questions with answers
- remove locked by android device manager message
- Android lock screen password not being recognized
- How to bypass lock screen in Cyanogenmod 7.2 (might work on other ROMs as well)
- Changed keyboard, now can't enter password
- Clear or reset my lock screen password/PIN
If you're still stuck and require further assistance, ask your question, indicate you've read this wiki and the linked questions, and make clear how your situation is different or where you're stuck.