Test somewhere harmless
Open a blank local text document and type a few letters and punctuation marks. Do not test by repeatedly entering a password into a real sign-in form; failed attempts can lock the account. Check the input-language indicator and select the layout that matches the keyboard. Display language and keyboard layout are separate choices.
If the issue appears only in a remote-desktop session or virtual machine, compare typing locally with typing in that session. Both sides may have input settings. Record which side produces the unexpected character before changing anything. A keyboard connected to another computer is also a useful comparison when available.
Keep the layouts you use
Review the installed input layouts in the system's language settings. Remove an unused layout only after confirming nobody sharing the account requires it. If you use several languages, learn the supported switching control and check the indicator when typing sensitive information. An accidental shortcut can explain an intermittent change.
Check whether an application has its own shortcuts or text replacement that affect the example. If a key fails in every layout and every application, inspect the keyboard connection and test another keyboard. A layout change will not repair a physically unresponsive switch.
After correcting the selection, test a short set of known characters again, then verify the sign-in screen's layout separately if that was where the difficulty occurred. Keep password visibility private when using any supported reveal control. For a workplace device whose settings return automatically, ask the administrator whether a policy is applying the layout. This is more productive than repeatedly removing and reinstalling the same language package.
