We are sorry to say that you are in a terrible situation!
I have two suggestions:
1) Take the broken disk to a specialized computer service and ask them whether they can repair/replace the electronic part (if replacement is to take place, you will need the exact same disk). This may help to make it operational again. If this procedure is successful then all your problems are gone!!!
2) It is possible to install new Domain Controller but you have to know that all previous security settings, user and group accounts, policies and other settings will be lost and must be reconfigured again. To do this, you will need an account-member of the local Administrators group to leave the old domain witch is not operational. This is done through:My Computer > Properties > Computer Name > Change button > Click Workgroup > Type any name> Then type username with administrative privileges and password.
After you have left the old domain you must install and configure a new one. Take a look at http://www.microsoft.com/windows2000/techinfo/planning/server/serversteps.asp
The next step is to do the same for all users. Once you are done, you need to join all users to the new domain. All users’ accounts must be recreated in the Active Directory Users and Computers
in the Administrative tools.
This is just the start - you need to recreate all previous settings, depending on the pervious configuration.
Murphy's Law: If you think that things may possibly go wrong – they always will.
Kind regards, Saiman, network administrator