Hello Denis and thank you for your answer.
Yes indeed, I'm really desperate but it's fine. Worst things are happening than lost data.
The reason for recovery was a faulty drive. Suddenly, out of nowhere, it was impossible to read it. But I didn't give up and I went on to plug it time to time and one day it "appeared" again on windows explorer as you can see on the picture attached.
I'm running windows 7.
You may see as well on the picture, following your questions, the info displayed and the letter, E, assigned to the drive by windows.
I also attach a pix of my disk management.
As you may see, the disk appears as Disk 3 but not initialized. When I launched the initialization process, it failed (message: "the request could not be performed...")
I'm afraid to unplug the disk.
These are all the info I can give right now. Thank you for your help and your time.