Windows PC says something to the effect of "User Not Found"

Have you also received the error “The User Profile Service failed the sign‑in. User profile cannot be loaded”?

Or did you get a notification saying you were signed in with a temporary user account?

You can go to Settings > Accounts > Your info, sign out of your Microsoft account and sign in with a local account, and then migrate your profile again.

Every morning when I start my computer, I encounter a message that roughly says "User Not Found," which prevents the system from loading my user profile, files, and desktop normally. To resolve this, I usually have to restart the computer, after which it loads correctly with all my files and settings intact.