If administrators and analysts change or if the iDRAC has not been used in a while, it may result in the iDRAC password being lost. It is simple to change the password but requires down time and a VGA connection to the console.
You will need have a monitor and keyboard or KVM attached to the server.
Reboot your server and press F2 during POST to enter System Setup. Select iDRAC Settings and then select User Configuration.
You can then change your username and password.