OK Toufiq, as is normal with your support it takes far to long for you to understand what the issue is and even longer to answer. We are now 12 days since i asked for this to be sorted. I could have finished the site using your competitors LMS (Guru) and still you do not understand what the problem is so i will again go over the problem yet again and ask that you read this at least twice before answering.
I build a course with say, 25 lessons, these lessons show in the backend as 1 to 25 as in the screenshot
I can move the lessons around into any order I like and like you and everyone else I would expect that on the front end lesson 1 in the sorted list (The first one in the list on the screenshot) would be the first lesson shown to the learner (student)
Notice on the screenshot that the first lesson with 1 in the box, titled "What? Why? Who?" is the first lesson.
However lesson 1 in the list shows last on the frontend, so i ask you to understand that the backend looks correct but the front end order does not reflect what is shown in the backend.
You will see from the attached front end screenshot thae "What? Why? Who?" is the last lesson and this is wrong. I or any of my staff cannot find a way to reorder this in options and the reordering options should reflect standard Joomla sort order
Please check this