You should have access to your account immediately upon reactivating an online course or extension.
You may need to log out of your myBlueprint account, completely exit out of your web browser, re-open your web browser, log back in and see if it's reactivated.
If that doesn't do the trick, you may need to clear your cache and cookies. To clear your cache and cookies, click on the Chrome menu in the top left corner of the browser, then Clear Browsing Data.
Clear the browsing history, cookies, and cached data, preferably from the beginning of time but at least to a point before the issue started. After that, sign out of your account, quit and restart your browser, and then log in again.