Cannot type user/password in UAC window.
Mostly, this issue is caused by missing Administrator account on the computer.
Go to Safe Mode to access the Built-in Administrator account and create a new Administrator account to resolve this issue.
To enter into Safe mode, follow these steps:
1. Restart the computer.
2. As soon as the system starts to reboot, press and hold the
F8 key until a black screen menu appear.
3. Select the
Safe Mode option and press the ENTER Key.
4. When the login screen appears, you should see the Administrator account there.
5. This account does not have a password associated with it by default.
6. Create a new Administrator account.
7. Restart the computer to check the result.
For more information about Built-in Administrator account, you can refer to the following article:
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