I have a Lumia 640 with Windows 10 Mobile. Lately the Photos app, when clicked to open, just closes immediately. How can I fix this?
Windows 10 Mobile has a nifty functionality that allows you to reset an app if it misbehaves. However, it is not available for most system apps, including Photos.
Try doing a soft reset. It usually resolves most app crash issues.
Whilst your phone is on:
Press and hold the Volume Down and Power buttons at the same time until you feel a vibration (about 10–15 seconds). Ignore the "slide down to power off" screen.