a. Press "Windows key + X" and click "Command Prompt (Admin)".
b. Type "net stop wuauserv" and press enter.
c. Type "rename c:\windows\SoftwareDistribution softwaredistribution.old" and press enter.
d. Type "net start wuauserv"and press enter.
e. Then run update troubleshooter as admin.
Basically what that will do is turn off store/update, then all the old files that make store work will be treated as old files that you can easily rename and use again, but it won't use them by default, then you'll start the store again, then the troubleshooter will put all the files back that you need, if this doesn't fix this, you might need to do a clean install of windows. Also before you do this reboot your computer and see if that fixes it, and make sure you know how to troubleshoot windows update as an admin.