In general, for login desktop black screen issue, we usually cerate exeplorer.exe process to fix it. However, the task manager is disabled, you need to enable it firstly.
Try to login with another admin account, then open local group policy editor, navigational pane at the left hand side, go to:
User Configuration>Administrative Templates>System>Ctrl+Alt+Del Options
Set "Remove Task Manager" policy as Disabled or Not Configured.
Log Off and Log in with your account, this time if you still get black screen, you could press Ctrl+Alt+Del to call out task manager, then create explorer.exe to show the desktop.
On the other hand, when you login as other admin account, you could go to C:\Users folder to find your user profile folder, which is named by your user account. All of your account personal files here.
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