Girl! I gotta tell you, this is my worst nightmare. NOT the flashdrive part. Just the misplacing ANYTHING. I am so OCD about keeping things in their place (do NOT read that as neat - I love an orderly "mess"). I go nutso if I do not hang up my keys in the same spot every day when I get home from work. OR whatever. If I put my keys in my pocket or handbag, I never check there at all - well until all else checked (even though common sense would say check there first). I go all over the flipping house checking, tearing stuff apart and having a fit saying much the same you say in your post about yourself.
I realize you think you left it at library. BUT, you may actually have it somewhere else that you just do not remember right now for your upset. And, since it is weekend, you will drive yourself batty until you can check at library if you cannot locate at home.
So I will suggest the following. Take it for what it is worth. But, it may assist you and you may gain peace of mind. OR, at least eliminate some possible places that you will have to check if you find it is not at library anyway. Do this:
Relax. Take a deep breath. Think.
Your OP is late evening Saturday night. From that point (8:45 CST) go back in your mind. Think. You know you were going to write for you went for your flash drive. But, what were you doing before? Then, slowly, while sitting down and not thinking on anything else:
Think backward methodically. On every detail. Jot them down as you go. With each thing you jot down move to the next. Then, when you have a list as complete as you can manage for Saturday, start at the BOTTOM of the list (as if starting your day and walking through it again). As you walk through all you did - you may run across your flash.
If not, do the same for Friday (of course school stuff may have to be put off on checking until Monday). Then Thursday. Perhaps your flash will be located on top of the frig - in the freezer - in your backpack stuck between the pages of a book - maybe you left it out and someone else in the house moved it for safe keeping and you need to ask them all. Who knows?
But, you gotta try for it will ease your mind that you have done all you can until you check at school. And, IF you do not locate it at home or at school, you will know you need to buy a new one - that you did the best you could to find it and that you will just start your nano over.
Best lesson?
You will find a secure and constant place for your flash in the future (keyring like someone mentioned) and this will not occur as often (hopefully) once you set up a pattern of where it goes ALWAYS.
Not trying to make you OCD. But, for something this important it cannot hurt to be very diligent.
Good Luck Blue!
Christine