Don't worry.  You haven't lost any of your recent training.

What has happened is that there are one or more questions in a previous section(s) that have been marked as incorrect and need to be re-attempted.

Just click on any quiz showing as incomplete and you will be taken straight to the questions concerned. 

Once you have re-attempted the questions concerned you will be able to continue from where you were up to previously. No correct answers have been lost.