I spent my entire day trying to figure what I am doing wrong and at this point I'm done.
While trying to rescue my main system I somehow managed to make things even worst and wanting to rescue at least a few files I have in the disk I decided to create a live medium, using the Windows I have in dual boot. I have used Windows to create USB installation mediums before, so I wasn't expecting the sort of complications I've met.
Usually I use Rufus. I grab a netinst, burn it and run i, as I l'm not aiming to rescue files. This time I opted to grab a bunch of live CD's, from Debian and a few Ubuntu flavours, just in case. The recording of the image I first picked went without a problem but when trying to run it, the system failed to recognize the medium as valid. I formatted it, by hand, picked a different ISO, repeated the process, and came to the same result.
I tried different programs: MultiBoot, YUMI, some other program that has a thumb drive stylized as a rocket for a thumbnail/icon... all ran flawless and every single time I tried booting the images the system failed to recognize it has a valid medium. At this point I considered I might have a faulty pen drive. After switching thumb drives, downloading fresh images and going through the same process I kept getting the same result: mediums are not valid. At this point I fetched a different machine. Maybe my fumbling went deeper. On a stable system, running a basically vanilla Bunsen Labs Hydrogen, installed from an USB, the images keep failling to be recognized.
In a last effort, I fetched an image of MultiSystem, yet another method that returned good results in the past. It works best with Ubuntu, so after fetching a new set of images, I moved to my entertainement system, where the only disc drive is, burned an image to a disc, booted the machine from it, installed a thumb drive with MultiSystem and a few more images, flawlessly, and tested it, successfully. The thumb drive loads, all loaded images are available and I even tried a live image of Xubuntu.
Happy and relieved, I went back to my main system and the thumb drive is not recognized. As well as on the Hydrogen machine.
Please, somebody share some ideas on this.
Thanks.