When Logged in to your Stardock account, Click on your avatar in the top right corner of the page and select Community>Settings. Here you will find four tabs. These include Profile, Login, Images, and Option. Go to the Login tab to see your user name and email address. Now, go to the Options tab and select "Auto subscribe to new posts and replies you create."
I don't know what could have happened to your avatar, but you can upload a new one on the Account Management>Account Info page. Make sure it meets the requirements 100x100 JPG or PNG file no larger than 40KB.