In order to fix this you need to contact Adobe and they will reset your Activation within 24-48 Hrs.
Note : No one else can fix this so don't waiste your time and contact Adobe.
To contact Adobe you can do following.
1. Go to www.adobe.com
1. Login to your Account..
2. Go to View Support Information
3. Choose Issue Type : Using a product or service and under choose product select Additional product and from the list select Adobe Digital Editions
4. Choose Additional Products - Digital Editions
5. Fill out the form. You can leave the Support Plan ID blank
I hope this will help you!!!