To Re-Register all Apps:
Get-AppXPackage -AllUsers | Foreach {Add-AppxPackage -DisableDevelopmentMode -Register “$($_.InstallLocation)\AppXManifest.xml”}




Reinstall Photos
http://www.intowindows.com/how-to-reinstall-the-photos-app-in-windows-10/

Step 2: In the elevated PowerShell, type the following command, and press Enter key to view all installed apps.

Get-AppxPackage –AllUsers

Reinstall Photos app in Windows 10 step2

Step 3: Scroll down, locate the entry named Microsoft.Windows.Photos, and copy its PackageFullName to Notepad program.

Tip: To quickly find Photos app entry, right-click on the titlebar of PowerShell, click Edit, click Find, type Photos, and then click Find next button.

To copy PackageFullName, select PackageFullName (refer to the picture below), and then use Ctrl + C hotkey to copy it.

Reinstall Photos app in Windows 10 step3

Step 4: Execute the following command to uninstall the Photos app.

remove-AppxPackage PackageFullName

In the above command, replace PackageFullName with the PackageFullName of Photos app that you copied to notepad in Step 3

remove-AppxPackage Microsoft.Windows.Photos_2017.35071.16410.0_x64__8wekyb3d8bbwe