Thanks for your answer and sorry for answering so late,

actually, I found a way to, following this topic http://www.talendforge.org/forum/viewtopic.php?id=8836.
1. in my new workspace named "bidule" (in the reinstalled Talend 4.01), I created a job the same name as the previous but with nothing in it
2. I quit Talend
3. I copied the files *.item and *.properties located in my previous exported job (with the same name as the new), and pasted them in Navigator-->yourProjectName-->process
4. I opened my workspace and the job (now re-filled) and could re-work on this job (starting from my previous exportation).
I did the same for the other jobs and it worked well.

Note :
- I did this with the same version of Talend than previously
- I realised that, after having worked and saved my re-worked job, if I wanted to export it in the same file as I put the previous exported jobs, I should first erase the previous export before and paste the new after. Otherwise it could add a new classification tree in my exported job file (especially when I organized the job in a different way in my new workspace= in new files in the workspace).

(I hope it is clear... if not ask me)

manuelle

well (after checking) yes indeed
actually, the box is checked by default !
thanks a lot