It is possible that your Userdata.psdb file got corrupt in the process.

Please do the following. Right click on the Windows Start Button, Left click on File Explorer. Click on the VIEW tab. Put a check on Hidden Files.

Click on This PC 

Now, go to C:\Users\Your Name\App Data\Local\PrintMaster\PrintMaster 2020

(Your name means the user name you're logged into)

Then, Delete the UserData.psdb file.

Launch the desktop shortcut and you should be able to register.