I don't know since when this started, but I just tried to open my Store app in Start and this happened. I could not open anything downloaded from the App Store, as well as open up my PC Settings. I tried MANY ways of solving this problem but none of them helped. I tried the sfc /scannow too.I got an error that says it has the detail in CBS.log

Have you checked CBS.log?

Hi,

Regarding current situation, please run the App troubleshooter to see if there is any error report:

App troubleshooter:

http://go.microsoft.com/fwlink/p/?LinkId=268423

Also, check this fix:

Fix Store App in Windows 8.1

http://blogs.msdn.com/b/notime/archive/2013/10/18/fix-store-app-in-windows-8-1.aspx

If the issue still persists, please help to export the event log and upload here via Skydrive or similar hard driver, share the link here:

Search event viewer -> click Settings and open Event viewer/ View event logs -> Under Applications and Services Logs>Microsoft>Windows>Apps

Also save the administrative log:

I want to add something I discovered. While trying a bunch of the suggestions for fixing the broken store issue, there is one important detail left out of the information given. I went through lots of so-called fixes because my original Microsoft account got totally broken when my organization did an Office 365 test using my email account which was already registered as my Microsoft account. So I had a personal and professional account with the same email address, and everything was totally messed up and the only solution I could find was to disassociate my work email with ANY MS account. Then my own little pain began. My PC with windows 8.1 had my broken email account as my MS account, and since MS did not have a way of changing an associated account with the App Store, I was forced to set up new profiles. I set up a non-admin for daily work and an admin one for other work. The non-admin account was a Microsoft account. Boom! more trouble! App Store wouldn't work. PC Settings wouldn't work and you can't run the troubleshooters with a non-admin account. Cute! So I made it an admin account for troubleshooting. And both "troubleshooters" said I wasn't using an MS account! Wrong!

So the fix that worked (and you must be an Admin to run it successfully), was:

powershell -ExecutionPolicy Unrestricted Add-AppxPackage -DisableDevelopmentMode -Register $Env:SystemRoot\WinStore\AppxManifest.XML

I also fixed another broken thing I fixed was setting Google as a search option, which didn't work as a non-admin. I am looking forward to Windows 10, which isn't supposed to shove the Microsoft account down your throat. It is especially inappropriate in a corporate environment.

I have used Windows since version 1 (yeah, really) and have been an IT Professional that entire time. This has been a royal pain and I won't use an MS account if I can avoid it. Too much pain in that mode.