Spells (not scrolls) dissapear. Any way to get them back?

[Ermac]

After multiple lost battles and returning to saves i noticed that my "Necro's call" spell is gone. (not scroll, i made it into a solid spell) I also didn't receive the "source of mana" spell/scroll or something by similar name after the turtle fight later, even though it said i did.

Now, i don't know about the second one, but necro's call was the only way to get higher tier undead creatures for me at the moment, because shops so far only sell ghosts and zombies, and graves are limited.

Since i had overwritten my saves, i wanted to ask: Is there any other quest, or place i can get Necro's call from, or should i start playing the game from scratch to get the spell back? :/

Thanks in advance, and i might as well add that the game is awesome