I installed Build 10061 about 3 days ago ... which broke lots of things that worked in Build 10041
Weather, eXcel Preview, Word Preview
And most importantly Windows Store (Beta) -- without this you cannot install/update any Win10 apps. I found three fixes
[1] from Win+R (Run)
wsreset.exe
[2] from an elevated CMD prompt
PowerShell -ExecutionPolicy Unrestricted -Command "& {$manifest = (Get-AppxPackage Microsoft.WindowsStore).InstallLocation + '\AppxManifest.xml' ; Add-AppxPackage -DisableDevelopmentMode -Register $manifest}"
[3] from an elevated CMD prompt
del /q %localappdata%\Packages\Microsoft.WindowsStore_8wekyb3d8bbwe\LocalState\*.json
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The first two did not work for me (nor for many others); option [3] did work
Hope this helps others; have been fighting this for 3 days