This article describes how to reset the Directory Services Restore Mode (DSRM) administrator password for any server in your domain without restarting the server in DSRM.
To Reset the DSRM Administrator Password
- Click, Start, click Run, type ntdsutil, and then click OK.
- At the Ntdsutil command prompt, type set dsrm password.
- At the DSRM command prompt: reset password on server null.
The null variable assumes that the DSRM password is being reset on the local computer. - Type the new password when you are prompted.
- At the DSRM command prompt, type q.
- At the DSRM command prompt, type q.
check this steps
http://profadmins.com/2012/04/09/to-reset-the-dsrm-administrator-password/
A few days ago, I have also experienced the problem of forgetting DSRM password, eventually I removed the password using this trick:
http://www.top-password.com/blog/how-to-reset-forgotten-directory-services-restore-mode-password-in-active-directory/
It’s also worth a try.