I have one suggestion...
Don't use fontbook.
Font Explorer X by LinoType is a much better option...and it's free!
🙂
If you have other questions about Font Explorer X, post them here and I will be happy to help.
As for fontbook, since you've been messing around in there, I would go in and DISABLE all fonts that you might have activated.
Then install Font Explorer X, and add your fonts.
As a general good practice, I keep all of my fonts that I am adding to my system in Macintosh HD/Fonts so that I always know where they are.
You have 2 user folders of fonts that apple installs, and one system folder of fonts. DO NOT EVER EVER EVER EVER EVER EVER EVER touch the System fonts folder. You will screw yourself royally. You shouldn't need to mess with your user fonts folders either.