Logon as Administrator or another user account with admin privileges.
If any other users are logged on, they have to logoff first:-
At the Welcome screen hit ctrl-alt-del TWICE. You will get a screen that will let
you type in the administrator account name and password or leave
the password field blank if there is no password.
If you don't know the administrator password you may be in big trouble.
Once you have logged in as the administrator, you can do this:
Right click on My Computer. Click Manage > Local Users and Groups > Users. Find
your user account in the right pane and double click on it.
I think you can then uncheck the box for "Account is locked out". (This is from memory, as I am not able to test it.)
After you are unlocked, go to Control Panel>Admionistrator tools>Local Security Policy and set the time for lockouts.
If you are lucky, you may have waited out the lockout be able to login by now.