First thing to do is check your SPAM folders and see if any lessons got caught there. If you do not find them there and are still missing lessons, please respond to us via email (or write a help desk ticket) so that we can investigate why the lessons might not be reaching you. Please make sure to add email@example.com to your whitelist / Allowed Senders list.
Secondly, at this point in time is is not realistically feasible to re-send any missing ACIM lessons. Fortunately, all the lessons are archived online and you can read them here.