If you store the hops in the original vacuum sealed packages, they'll keep a long time, especially in the freezer. If you have a food-saver and reseal then after you open them, and pop them back in the freezer they'll also stay a very long time. I'm still using up some of the 2008 hops I bought. My freezer is FULL of hops- I have more than 156 ounces of hops in my freezer at this moment.
When you open them, smell them. If they smell good, and not "cheesy" or stale, they should be fine.
If the hops you have were dried properly, and frozen properly, they should be ok. But they should still be aromatic and "fresh" smelling. If they haven't been frozen, but just kept in a hot garage, they're probably not something you want to use.