How to get user name and password for data connection authentication?

Hi,

My reports are not refreshing on Power BI service because some credentials aren't being validated as they are set to skip test connection. In order to uncheck the "skip text connection" box, I need the username and password. But i dont know the username and password since the person that used to manage the gateways has left the organization. Is there a way to locate the user name and password?