How to open administrator account without password?

Third party tools have been developed that help you reset your Windows password. My personal favorite is "Active @ Password Changer". The software finds the registry key that contains your passwords and gives you the option to remove the password from any user account. Moreover, the software works for almost every version of Windows out there both 32-bit and 64-bit. It has both DOS and Windows versions.
I prefer the Windows version since it uses a simple graphical interface and it is a lot easier to use than the DOS version.

By default installation, Windows XP has a built-in Administrator account which equivalent to root or superuser privilege account in Linux or Unix that contains no password.
see for further details : http://www.mydigitallife.info/easily-login-to-windows-xp-with-no-password-administrator-account-backdoor-trick/

It is difficult to say. May be some software present online.

dnt knw

These days many online tools are available which helps you to crack any password. 

There are many online supporters for removing password.

Well there are few apps using which you can remove that password. But they are risky as it can do something unwanted.

There are online computer services that can help with your problem but I recommend installing ophcrack, it's easy to use

Try google search and many online password crackers are available.

Just login to some other user if you have and then open the "Run" window. Then type the command "control userpasswords2" and click OK. You will be shown all the users on the computer. Click on the administrator and click reset password. Type the new password and click OK.

Now you can Log off and Log in again as an administrator using the new password you provided.

(Note: This will work only if the user you logged in has the neccessary permission)

Online password crackers are present. you can search on google for such things.

I cannot try to hack administration password.