No, not exactly. Magic is a sort of energy, the same kind of energy gods use to create. The difference between us and the gods is they can channel more of it, and they can access that energy in places we can't.
Fillory was a source of that energy, it supplied magic to hundreds of other worlds. Without it, those worlds were cut off. The wellspring in Fillory was shut down (long story) and order to turn it back on and bring magic back, I had to sacrifice my power.
So, I know how to do magic, I just can't currently channel it. On the plus side, sort of can't be affected by most of it either right now.