Go to helpx.adobe.com/contact.html. The first site that comes up will be "Contact Customer Care". It will ask you what product you need help with. Click on Adobe Digital Editions. It will then ask you what do you need help with. Click Adobe ID signing in or something to that effect. A blue bar should pop up asking if you still need help. Click on this blue bar and a form will pop up asking for a brief description of the problem. Tell them you need your Adobe ID authorization number reset.
Some of the techs are better than others. They have to reset your activation count from their system. A good tech can do this in 5-15 minutes. Once they have successfully reset the number wait about 10 minutes before you activate your new device because it takes a few minutes for your number to reset itself. I have had much success with the live chats because most of the techs are pretty knowledgeable. Just let them know all you need is your number reset so you can use your TABLET. Otherwise they will give you the instructions for activating a PC. I've had to contact live chat about 10 times in the past few months because I am always experimenting with different apps and constantly exceeding my limit.