I hadn't played Skyrim for over a year. I came back and started to play and everything was fine. I then conjured a frost atronach. When I later tried to summon another one, it wouldn't work.

I thought maybe it was because of the cultist cave I was in, so thought nothing of it. So I finished that quest and as soon as I fast traveled into a town during the day, the Dragonborn dlc quest was triggered, that I had never played before(doing some dlc stuff was partly why I came back to play again). At this point the game has gotten more and more buggy.

I cannot do any magic at all by this point. When I started the dlc, I still could not summon(although maybe 1 in a hundred tries it will let me summon something). But i could still cast restoration and destruction, etc magic.

Now though, no magic works. I can't conjure, heal, destruction, illusion, nothing.

What is going on?

I even tried going back to save of mine from Feb 2013 to see if it worked. I could do magic right off the first time(it lets me cast something one time), but afterwards, no magic again.

As far as I can tell I have no diseases, or absorbtion spells/items that hinder my magic abilities. And like I said it was working fine for quite a while and has just gotten worse and worse.