Finding molar mass of an unknown acid "In the titration of a solid acid, an endpoint is reached after 22.0mL
  of 0.120 M $\ce{NaOH}$ has been added. Assuming that each acid particle
  contains two acidic hydrogens and both are neutralized, what is the
  molar mass of the unknown acid?"


I really don't know how to solve this. I've figured out how to calculate the moles of acid were in the sample but don't see how to find the molar mass from that...any ideas?
Your data is not enough to calculate molecular weight. You may have missed the mass of the solid acid you have weighed.
Let's assume you have weighed $a$ gram of acid. Then:
$Molecular Weight = \frac{Weight}{Moles_{acid}} = \frac{Weight}{2 \times Moles_{NaOH}} =  \frac{Weight}{2 \times Molarity_{NaOH} \times Volume_{NaOH}} = \frac{a}{2 \times 0.120 \times \frac{22.0}{1000}}$