I can't feel anything in my ring and pinky finger on my left hand. It happened in Year 11, when I was 16 - I was setting up a nice big set of amps for a band practice ahead of a small gig when it toppled and crushed my hand and arm. All I could feel for months afterwards was an awful tingly sensation right down my arm and hand - kind of like permanent pins-and-needles. I had to go to a physiotherapist and everything, but all he could do was tell me not to drop amps on my arm again. Over time, my arm and half my hand's recovered, which was lucky and not a little bit useful, mostly because I can play guitar properly-ish again now.There's no scarring or anything - the only inkling people have about it is the fact I sometimes fumble notes if I play using them, which I try to avoid. Also, I once managed to cut my fingertips pretty badly because I was pressing down really fucking hard on the strings because I was so confused as to why I couldn't feel them, so we sort of realised something was wrong when blood started running down my fretboard.
But yeah. Can't feel a thing in the last two fingers, and I haven't been able to for the last 4 years.