If you have partner contract (NIC-REG) you need an official letter to restore your password.
If you have customer contract (NIC-D), administration password will be sent to e-mail address provided in the "e-mail" field of the contract (form), in case you have not forbidden doing that in advance.
If the address is invalid, you will need an official letter to restore password.
If you have forgotten NIC-D contract (form) number, specify domain name to have password sent to you
Reminder: according to clause 3.2.3 of service contract, the customer commits to take all risks of unfavorable consequences due to loss and/or disclosure of the customer's password.
If you have forgotten technical password
You can change technical password in the "Manage your account" section ("Change password" link) when logged in using administration password.