You signed into Windows 10 with the Microsoft account that you use for OneDrive and OneDrive still saying not signed in.
1. Exit OneDrive (right click in the system tray)
2. Go to Control Panel > User Accounts > Credential Manager
3. Click on “Windows Credentials” (on the right)
4. Choose the down arrow to the right of “OneDrive Cached Credential”
5. Choose Edit, and enter your OneDrive (Microsoft Account) Username/Password.
6. Go to the start menu, and launch “OneDrive” again
This may restore your OneDrive without resetting your local copy.
Alternatively, simply remove the “OneDrive Cached Credential” (there is an option to do so) and let OneDrive start over. The positive side is IF you wanted to move your OneDrive to another location, you’ll have the opportunity to do so during the reset. Either way, you will NOT lose your online data.