The rescue system for a root server can be activated in the customer center. To activate rescue system please log in to the customer center, select the respective server contract and select the entry "Rescue-System" from the left menu.
After activating the rescue system it takes about 5 minutes until it's provided by the system. Afterwards you may either start a web reset or a reboot in the console and start the server with no access to the hard disks of the server in the rescue system.The login takes place with the default password of the server.
Depending on your servers hardware it takes up to 60 Minutes for the rescue system to boot.
If your server tariff doesn't contain a rescue system it is not possible to enable it in customer control center. The only possible way is to change the server tariff into one providing the option "Rescue System".
A detailed instruction how to use the Rescue-System offers our EUserv Wiki: