Cortana

How do you repair a corrupt user account?

- system restore (but you don't have any restore points)
- restore a disk or system image (but you don't have those)
- create a new user profile and transfer data to that, and configure programs to start up appropriately in that, and delete the old one.

But.. you say the Store isn't working at all, in any account, whilst Cortana works only in your admin account.

Can you try creating a new user for test purposes, and advise if both work in that?

And you can try
Windows Store Apps Troubleshooter - Run in Windows 10 - Windows 10 Performance Maintenance Tutorials
Store - Re-register in Windows 10 - Windows 10 Performance Maintenance Tutorials
Clear and Reset Store Cache in Windows 10 - Windows 10 Performance Maintenance Tutorials

However, I suspect you may be heading for a clean install.
Do you have full data backups?

Oh.. that one. Please try it in a 'normal' admin account. And please try the suggestions in my previous post.

As an in-place upgrade repair didn't help, the question is whether your user profile is corrupt. Hence try creating a new one.

Good - and not so good. That means your old account is damaged or corrupt, but Windows per se is ok.

So, your choice is
a. Configure and use your new account (Move data, set up startups as the old account, any settings etc)

Note: you cannot simply log in as one user and copy data from one user to another, unless logged in as admin and copy files between standard users.

You could use Kyhi's boot DVD/flash drive (top of the Software and Apps section), boot from that, then, being very careful about which drive letters and folders you are accessing, copy files that way.

Or, you could log in to one profile, copy files to a folder not part of the user profile- e.g. to a separate disk or partition might be simplest- log in to the new profile and copy them back again- being two copy operations, which is less desirable.

Start-ups: for traditional 'desktop' programs, you should reinstall those that don't start up when logged in as the new user, so all their relevant folders are created in the appropriate places.

I was looking for a guide on doing this as I've note mentioned store apps in the above- which would require your new account to use the same login id. However, I've not found one.

Thus, guessing, I'll add you may also consider changing your old profile to a local account, then creating your new profile with your existing login id. Note: I've never done that, so that's an assumption, but should mean you have access to your present store apps and can download them again.

or
b. Continue to try to fix the old account.
E.g.
http://www.thewindowsclub.com/windows-store-apps-troubleshooter-for-windows-10
https://www.tenforums.com/tutorials/3175-reinstall-re-register-apps-windows-10-a.html

Re-register Store app in Windows 10 - Windows 10 Performance Maintenance Tutorials

Assuming you can't fix the old account and need to create a new user, and considering the data only:

You will probably have personal data in your user profile. For example:


and any other folders you may have created.

All those are particular to a given user. Delete that user's profile (account) and their desktop, Documents, Videos etc will be gone. Nada. Deleted.

Thus when you create the new user's profile, that user's Desktop, Documents etc will have no personal content.

You need then to transfer the contents of the old user's Desktop, Documents, Videos etc to the new user's folders.

You cannot do that when logged in as a standard user.

Now, installed programs (especially multimedia programs) fill these typical folders (which are just created by Windows for your convenience) with their own folders. These are created when you install such programs.

Do not bother copying those. Indeed if the program is installed 'for all users', hopefully those folders will be created in the new user account.

Thus where you installed programs only for 'this' user, you will need to reinstall such programs either for all users or for the new user only.