Hi I ran into the following problems a few times.
As operating system I use debian 10 (.2 gnome) and ubuntu 18, 19, (recently 20).
Question 1 An external hard disk that I use (which is I think possibly failing) was formatted in NTFS. While I was working on a machine at the university where I used to work, all files disappeared, and reappeared and the format of the disk was changed to FAT or something like that. I have no idea why and how this happened. Does anyone have any clues
Question 2 I use usbs to store the files I work with. Quite a few times when working with linux systems, the usbs refused to mount, giving wrong fs type blaah blaah error. This was a usb that I used and stored files to working under linux, and I do not remember the exact format on the disk. I tried various programs to recover the files, and in some cases I was able to recover some in other cases I was not able to. Sometimes I was able to format the usb to be able to use it again, a few times I was unable to. What methods are available to recover data, and what to do when something like this happens.
Thank you in advance