I bought Cakewalk Sonar Artist around two years ago since then I have download the free version from Badlab.
Three days ago the software defaulted to Demo Version meaning I cannot save my work  
When I try to contact Cakewalk on line it says that I am not eligible for this service.
I have the software on two PC's and the problem is the same on both.
Help !!!

Not clear if the activation issue is with SONAR Artist or CbB. If it is CbB start with this http://forum.cakewalk.com/FindPost/3788538. If Noel's advice does not work, please post here again.
 
FYI - BandLab Support info

Do you have a Cakewalk account?
 
The last time I checked the SONAR versions could still be activated online via those accounts, either by installing using CCC or by the offline activation procedure. 
 
https://www.cakewalk.com/Support/Knowledge-Base/2007013384/Offline-Activation