If you encounter this error message in your SharePoint environment the first place to look is the logs, but there's a very good chance that this relates to a password problem for one or more accounts running one SharePoint's IIS application pools.
Check IIS > App Pools and identify the accounts used by your app pools.
Open AD and ensure that these service accounts are configured so that the password never expires and the user cannot change the password.
Reset the password(s) as required.
Return to IIS > App Pools and right click each SharePoint related one and select 'Advanced Settings'
In Process Model > Identity, click on the ellipses
Type in credentials and OK
You may also need to manually restart the Application Pools affected by the change.