In order to cast spells, you need skill points allocated to the spell trees. I believe you can allocate some basic points at character creation, and at level up. The most basic spell is in the Fire tree, and you get it after only 2 skill points in this skill.
Your magic is only going to get you so far in some of the longer fights, so being without magic is not all that unusual for a mage. If you can't cast spells and you don't want to reroll, you can always use back row attacks, like throwing rocks, using a bow, or using the reach weapon, this spear.