Photo app in Windows 10 stopped working

No, resetting will not delete your photos, those are kept in your Pictures folder and will automatically be populated there when you launch Photos again.

Reset / Uninstall / Reinstall will not make you to lose the photos.

Try following and check after each step

1. Run Windows Store Apps Troubleshooter
Type troubleshoot in Windows Start Search box > Click Troubleshoot > Scroll down to bottom and click Windows Store Apps > Click Run the Troubleshooter and follow on-screen directions.

2. Reset Photos App
Windows+X > Settings > Apps > Apps & Features > Locate Photos by Scrolling Down > Click Advanced Options > Click Reset

3. If Reset doesn't work, then you should uninstall using Powershell and reinstall the Photos App
Windows+X > Click Windows Powershell (Admin) > Copy the below command and right click in Powershell to paste it

get-appxpackage Microsoft.Windows.Photos | remove-appxpackage

Now, you need to reinstall it
Use below Powershell command to install

Get-AppxPackage -allusers Microsoft.Windows.Photos | Foreach {Add-AppxPackage -DisableDevelopmentMode -Register “$($_.InstallLocation)\AppXManifest.xml”}

4. Reset the Database of Photos App
Copy following and paste in Windows Start Search box (Replace Your User Name appropriately)
C:\Users\Your User Name\AppData\Local\Packages\Microsoft.Windows.Photos_8wekyb3d8bbwe\LocalState
Click on result and delete everything from inside the folder

Source - https://answers.microsoft.com/en-us/windows/for...

Hi Linda, resetting will only reset the app and your app settings, you photos will remain untouched . . .