Why my iPhone password locked?

If you mean your Apple ID password, click the link below that most closely matches the disabled message:

• If you see a message that says 'Your account has been disabled in the App Store and iTunes' - Apple Support - note that resolving this requires contacting an iTunes & App Store support representative using the link in the article; you cannot resolve this on your own
• If your Apple ID is locked or disabled - Apple Support

If you mean your iPhone screen lock passcode, If your device has iOS 15.2 or later installed, you can reset it without a computer; check out this link→How to reset your iPhone, iPad, or iPod touch when you forgot your passcode - Apple Support. Otherwise you will need a computer:

See this Apple support link→If you forgot the passcode on your iPhone, or your iPhone is disabled - Apple Support

Or watch this companion video ⬇️

After restoring the phone using one of the methods above you can restore your most recent backup.