Multiple applications have stopped working, since upgrading to Windows 10 version 2004

Rod-F  

The symptoms are there to show, there's no other way to check a user profile. 

Let's suppose your current user is rod and the new user is falanga 

Open a Command prompt (admin) and type: 

net user falanga yourpassword /add 

net localgroup administrators falanga /add 

xcopy %userprofile%\desktop\*.* c:\users\falanga\desktop\ 

repeat for any other folder which contains useful info (pictures, documents, music, downloads and so on) 

Just a bit of caution, if you have folder backup set to Onedrive (which I recommend) the commands for the following folders will change like this:

xcopy %userprofile%\onedrive\desktop\*.* c:\users\falanga\desktop\ 

xcopy %userprofile%\onedrive\pictures\*.* c:\users\falanga\pictures\ 

xcopy %userprofile%\onedrive\documents\*.* c:\users\falanga\documents\ 

Check this before by right clicking the Onedrive icon in application bar, Settings, Manage backup. 

Then, in Settings/Account, change rod to local user.

Disconnect rod and log in with falanga. 

Also in Settings/Account connect falanga to your Microsoft Account and you should be done. 

Probably some apps will need some settings to be redone, but the main part is transferred. 

When you're happy with the new profile, you could delete the old one. 

Feel free to ask questions if something is not clear.