0_o... That is a lot of sketches. I'm wondering... do you lose interest on a drawing/painting? Do you have any tips for being concentrated one one art? It's because I draw a lot, but just, I lose interest in them and I don't finish them. You know, just curious...
Yes, I have several unfinished pictures and sketches. If you loose interest in a particular piece it can't be helped. Focus on what you enjoy!
You could focus on the aspects that made you start a picture and try to hang on to them. Or just let it be, start some new pieces and maybe get back to it some time later.
Or you could just run with it and make collages of your best sketches - even if they are unfinished or rough - just to have a sense of having accomplished/finished it in some way (for the moment) - I did that with many of my early sketches.