If you have not set password for administrator then you can do the following

On the log in screen that doesn’t show the administrator account you can press ctrl+alt+del twice and it will take you to the classic style log in screen and you can change the username to administrator and leave password field blank and log in that way. After login you can create new user or update/remove existing users.

Shere,

Thanks for your input, but unfortunately i had set administrator account. I cant remember the password. Any workaround ??

What you can do is log onto a working computer that has a CD-RW drive and internet access. Download a program that is called OPHcrack. This download will be an ISO file. Burn a bootable copy of the ISO file. Once the burn is done, then return to the computer that you are locked out of. Have your computer boot from the CD rom drive with this disc in it. OPHcrack runs on its own and will crack your PW and any other PW that has been logged in the SAM file on the windows machine, regardless of PW complexity. KEEP the disc for later use if you so happen to need it again.

Check this. This has worked for me.
http://pogostick.net/~pnh/ntpasswd/
http://pogostick.net/~pnh/ntpasswd/walkthrough.html

Use trinity Rescue kit

Hacking Gig. cool.

i have tried all of ur suggestions but no success. I had put 8  alpha numeric character as password. Any other suggestion would be highly apprecieated!  

only way to get rid of it is reload the program (OS) from CD if you have it.

Yup reinstall the OS, I guess that would be the best idea. You might get a password recovery software but it might cost you a lot.

Try using nasty nepali words. usually guys put dirty words for PW.

Looks like you did not use the tool right way. Just saying they did not work is not going to help you. You got to tell us where it did not work if you want help.

Here are the steps again:

Download this iso image and burn it on CD. Burn it as an iso image.
http://pogostick.net/~pnh/ntpasswd/cd080802.zip
(Alternatively, you can do it from floppy with this http://pogostick.net/~pnh/ntpasswd/bd080526.zip )


Go to your BIOS and select to boot from CD. It should boot the linux kernel. Then it will prompt with messages something like this depending upon your windows system.:


Disks:
Disk /dev/sda: 42.9 GB, 42949672960 bytes

Candidate Windows partitions found:
1 : /dev/sda1 40958MB BOOT

Please select partition by number or
q = quit
d = automatically start disk drivers
m = manually select disk drivers to load
f = fetch additional drivers from floppy / usb
a = show all partitions found
l = show propbable Windows (NTFS) partitions only
Select: [l]

Follow the procedure on http://pogostick.net/~pnh/ntpasswd/walkthrough.html .
I could not be more descriptive than what it is written in above site.

Make sure you do not change the password for Administrator but rather clear the
password. And the change it after wards login to thw windows with blank password.

Also, make sure you completed the task by writing to the file after you have rest the password.
I have used it and worked for me several times.



I hope it helps. Let us know if it did not and where your got into problem. Try to be as more descriptive
as you can before asking for help.

Look for ERD commander.
Burn the software to cd.

Boot form CD.

Reset the password to whatever new password you can remeber.

Hurray.

great info