You normally don't have to type in your email password in your email client, so I was wondering
- are you using the program Outlook as included in MS Office, because sometimes 'outlook' is used to refer to a MS outlook account
- is it a new account that you just entered in your PC
If you forgot your password you normally have to go back to your service provider to reset it.
Some of the older versions of Outlook, the password saving feature would corrupt the saved password every now and then. I would go the web version of your mail provider gmail.com or outlook.com etc and try and login there. If your password does not work then you will need to reset through the mail providers website and then change it in Outlook.