Reasons why you can't unlock your phone or why your phone's lock screen may seem to be stuck or frozen include:
- The device has low operating memory.
- The device's storage is full or almost full.
- The device has a temporary software error.
- A Secure Digital (SD) card (aka removable memory card) is inserted that has corrupted data.
- There's interference with the touchscreen from:
- The screen protector or phone case.
- Lotion or dirt on screen or hands.
- Wearing gloves when using the phone.
- An installed app.