This message appears after too many wrong passcode attempts. Short lockouts escalate to longer waits; eventually the device may require a computer.
Unlocking without the correct passcode is not possible without erasing the device (unless you have a backup path). Plan ahead with regular backups.
Use our DFU & Recovery guide to enter Recovery mode, then restore with a trusted computer. Review iOS errors if restore fails.
Restore from iCloud or a computer backup if available. Without a backup, you set up as new.