If you have received the message "Department cannot be blank" when attempting to reset your password this means that when your user was created it was not assigned to a Department. Due to this your account will need to be updated with this information so that you will be able to log in once more.
In order to do this you can reach out to your local Simplee Admin as they will be able to edit your user and assign you to the correct Department. If you need additional assistance in getting this resolved you can also reach out to Simplee Support by sending an email to support@simplee.com.