deleted .... again!
several times i have been part way through an exercise and it is suddenly terminated and i have to start all over again. is your computer or mine at fault?
If it keeps on happening with different browsers and/or different computers, I suggest that you use the "Support" tab on the left side of the site to ask the Duolingo team if there is a problem with your account. But if it works normally with at least one browser and/or computer, then the problem is more than likely on your end.