Question about bikes?  

I know nothing about bike terminology, but I recently got my mom to bring me my old mountain bike to the city I live in now. Unfortunately, at some point during the winter, my dad accidentally backed over it's rear wheel, so I'm thinking the entire thing needs to be replaced since the spokes are all broken and it's bent and pretty warped looking.

I guess I'll need to get a new one, but I need to know from someone in the know about mountain bikes, what kind of things a bike shop would need to know to replace it, what exactly I'm going to ask for (so I don't look like an idiot trying to explain) and what kind of price I could be expecting to pay for something like that?

Thanks in advance, guys!