If you are going to create a new web application from the central admin that time if you got the below error then follow the below steps..
Error : The password supplied with the username was not correct. Verify that it was entered correctly and try again.
Solution : Open “SharePoint 2010/2013 Management Shell” run as administrator and then type the below command to upgrade the password
stsadm -o updatefarmcredentials -userlogin domain\username -password yourpassword