Outlook says your password is wrong but it's correct

The fix

Clear the stale credential and sign back in

Follow these in order. None of them delete your emails — your mail lives on the server and simply re-downloads.

1. Close Outlook completely. Right-click the taskbar, choose Task Manager, and if Outlook is still listed, select it and click End task so it fully shuts down.
2. Open Windows Credential Manager. Click Start, type Credential Manager, and open it. Click Windows Credentials.
3. Remove the Outlook and Office entries. Scroll to Generic Credentials and look for anything starting with MicrosoftOffice, Outlook, OneAuth, or MicrosoftAccount. Click each one, then click Remove. Removing these only clears the saved password — it does not touch your emails.
4. Restart your PC. A quick reboot makes sure nothing is still holding the old credential in memory.
5. Open Outlook and sign in fresh. When it asks for your password, type it carefully and tick Keep me signed in if offered. Outlook stores a new, correct credential and the loop is gone.

If your provider uses 2-step verification (many Microsoft, Gmail and Yahoo accounts do), your normal password may be rejected by the desktop app. For a modern account, Outlook will usually pop up a browser sign-in window and ask you to approve it on your phone — complete that and you're in. On older setups that can't show that window, Gmail and Yahoo still accept an app password instead, but Outlook.com and Hotmail need a newer Outlook that shows the browser sign-in.

Finally, an out-of-date Office can keep failing to authenticate the modern (OAuth) way. In Outlook go to File > Office Account > Update Options > Update Now, let it finish, then restart. This keeps Outlook on modern authentication, which providers now require.