It certainly sounds like you are working in a temporary profile rather than your regular user account. The temporary profile was created for troubleshooting, when your regular user account has problems. As the name says, it's only temporary so nothing in a temporary profile is saved when you restart your computer.
Here, from Gemini AI, are the most obvious signs that you are in a temporary profile:
- Upon logging in, Windows typically displays a notification in the System Tray stating: "You've been logged on with a temporary profile" or "We can't sign in to your account."
- Custom desktop wallpapers are replaced with the default Windows 11 background, desktop shortcuts disappear, and browser preferences/bookmarks are absent.
- Folders such as Documents, Downloads, and Pictures appear completely empty or revert to default states.
Here's a more technical method - also from Gemini:
Go to Start > Windows System > Command Prompt and type: whoami/user
If you are in a temporary profile, the result of running that command will include the word TEMP.
If you discover that you are working in a temporary profile, you need to figure out what is preventing you from signing in to your regular user account.