Change the domain name in the dropdown to the name of your local computer,
then log on with your local account.

If you don't see a domain drop down list, then click the advanced button to
display the domain drop down list, and then change your domain name to your
local computer.

If you don't see a dropdown list or an advanced button, then log onto the
machine using a domain account.

If no domain account has access to the machine, then have someone that is a
domain admin logon to the machine and grant a domain account access, then
log onto the account (Or have the domain admin reset your local account
password [warning you'll loose personalized information]).

If all of this fails for various other reasons not covered in this note;
then google for ways to reset passwords when you can't log onto a machine
anymore.

If that fails, or you can't figure out or find out how to do that; get your
restore disk, and hope you have a backup.  :)