Before resetting you password, make sure your keyboard's Caps Lock is off, because passwords are case-sensitive. Then, try logging in again.
If you are already a member of DEWALT.com click on the login tab at the top of the page. There will be a box that pops up and in that box it will show "forgot password" and you will need to click on that if you forgot your password. You will be asked to enter your email address so a password reset link can be sent to you.