How to Unlock an iPad or iPhone?
How to unlock an iPad or iPhone depends greatly on which particular lock we’re discussing...
There are different locks involved, and all unfortunately commonly called locking or unlocking.
Carrier Lock.
Carrier locks are used to tie a device to a particular carrier network, usually as part of a purchase subsidy for the device. Upon payment or completion of the contract, some carriers will offer to unlock the device for use on other networks. Other carriers will not unlock a device.
Carrier lock questions arise with iPhone and rarely if at all with iPad, and most folks don’t grumble about this being unlocked.
If you've acquired a carrier-locked device as part of a purchase, you may need to have the previous owner request the carrier unlock as they're the ones that had the cellular plan. And in some cases, you're going to end up paying for the remainder of any cellular plan, if the previous owner transferred the device before completing the plan that provided the purchasing subsidy.
Here is: How to unlock your iPhone for use with a different carrier - Apple Support
SIM Lock.
A SIM lock is a passcode associated with the SIM card in use. You’ll need to discuss this SIM unlock with your carrier, if you do not know the SIM PIN or PUK associated with the SIM module.
Use a SIM PIN for your iPhone or iPad - Apple Support
Screen Rotation Lock.
There is the screen rotation lock.
Rotate the screen on your iPhone or iPod touch - Apple Support
Screen Auto-Lock.
There’s the screen auto-lock mechanism. That’s controlled from the Touch ID & passcode or the Face ID & Passcode settings, depending on your device.
Activation Lock.
Activation Lock is intended as a theft-deterrent mechanism. A theft deterrent that is easy to bypass would not be much of a deterrent.
Nobody here in the Apple Discussion Forums can help you clear Activation Lock.
To clear an Activation Lock, you will need the password of the associated Apple ID, or the original purchase receipt and a discussion with Apple Support, or similar proof of ownership.
If this device was recently purchased and the seller is still available, contact the seller for remediation or for refund. A remote unlock using iCloud is available to the person with the Apple ID holding the Activation Lock, if that person is still available and is inclined to unlock this device.
Again, only the person with the credentials to the Apple ID holding the lock, or Apple, can clear this lock. For Apple to clear the lock, you will have to provide a receipt with proof of original purchase and with matching serial number or IMEI, legal paperwork from an inheritance, or other similar proof of ownership materials.
For recovering access to your own Apple ID, if you are the holder of the Apple ID associated with the Activation Lock:
If you forgot your Apple ID password - Apple Support
If you forgot your Apple ID - Apple Support
How to use account recovery when you can’t reset your Apple ID password - Apple Support
Contact Apple for help with Apple ID account security - Apple Support
If you are the heir:
How to request access to a deceased family member's Apple accounts - Apple Support
Purchasing devices with Activation Lock is unfortunately far too common. These are scams, and other fraudulent sales. These locked devices will not be useful to you, and are probably best recycled. See the following link for more info:
The All Too Common SAD Reality of Buying a Used iPad/iPhone
Passcode Lock.
The device passcode or password is what you use to access your iPad or iPhone, and is what protects the data stored in the iPad or iPhone. Touch ID and Face ID provide a way to avoid having to enter the passcode or password as often.
Your device security and the data storage encryption protecting your data is based on your passcode or password, and you will need to enter that passcode or password every few days or so to re-enable Touch ID or Face ID access, depending on your device usage.
If you have forgotten the device passcode or password, you will have to reset and erase the device—again, the passcode is what protects your data, so resetting it renders the existing contents inaccessible. Here's how:
If you forgot the passcode on your iPhone, or your iPhone is disabled - Apple Support
Screen Time Passcode.
Screen Time can be used to control or restrict access to some features of your devices, or can be used as part of Family Sharing to control aspects of a family member's devices.
The screen time passcode can be reset using the following procedure:
