First start/reboot yout PC press F8 while booting (After BIOS POST).

Select SAFE-MODE continue.

After that then login-screen will appear with n+1 accounts to login.

where n = no.of active accounts on your PC.

That extra account will be named “Adminstrator” with no pass by default.

Just logon to that account.

Now goto ’start->run’ type ‘cmd’ and hit enter.

To get the list of existing user accounts type “net users” .

Now,
type “net user < your username > *” and hit enter.

It will ask you for password twice - its upto you either enter a new pass
or remove old pass by hitting enter twice and thats it!

Now reboot and you can login to your account.

If this account is password protected then there is little hope to remove your password.