Sorry, there is no way to recover the save from before it was over written. <img src="/ubbthreads/images/graemlins/disagree.gif" alt="" /> The latest patch also rotates between two (by default) different quick saves.
Mage spell books can be bought; try Kistandalius or Blake in Ars Magicana and Corinna or Mpenzak in Verdistis. If you quick save before talking to them, hitting alt or running your mouse over them, you can quick load if they don't have what you are looking for.
There are a couple curse skills (one is better than the other, IIRC) which you should be able to cast on him a couple times to make him susceptible to Freeze.
