Click the 'Account' icon in the navigation bar at the top of the page. It's in between the 'Search' and 'Cart' icons as shown in the image below. You will be redirected to the Login page.
Next click on the 'Forgot your password?' link underneath the login in form as shown in the image below.
You will be redirected to the Reset your password page. Proceed to enter your email address, then click the 'Submit' button.
An email with a link to reset your password will be sent to you, click the link and you will be redirected to the 'Reset account password' page. Proceed to enter a new password into the provided form, then click the 'Reset password' button.