Okay first of all i'm so sorry for the misunderstanding word about the "tab" as it really is called a download "window"...... my bad, i didn't realise it until you pointed it out hehe... (not a native english speaker there)
So i managed to fix the problem. When i unninstalled the app i didn't realise there were some files left in the 'Local' and 'Roaming' AppData folders so even after re-instaling the app i would have the same result as an invisible and impossible to interact (to answer both your questions ; and the windows-key + the up-arrow-key didn't work either) download WINDOW.....
So before re-installing the app for the million'th time i deleted all the remaining files in there, of course saving my games folders that were in the 'Roaming' itch folder as well as the "RenPy" folder where all of the persistent files are somewhere safe until i put it all in again, so i dont't loose all of the saves and progress in all of my games, and made a clean new install.
I guess the issue was the remaining itch files inside the 'Roaming' folder because i finally have access to the download window again !!
I still have no idea how the problem happened but when you mentioned that Windows store properties in apps and that it somehow screwed up the download window i had the idea of a clean new fresh install.
So i want to thank you for taking the time to answer me and my stupid brain !
And again sorry for the misunderstanding and my poor choice of word haha !
I hope you have a good day/night !!