How to Remove bearings from skateboard wheels.

To add on to this comment... Bones Reds are a great bearing for their price: [LINK] Here's a quick video on how to remove bearings from a wheel: [VIDEO] And here's a quick video on how to put the new ones in: [VIDEO]

As Blushine said, the bearing are what allows your wheels to turn. Just pop them out [VIDEO] and replace them, and you'll be ready to roll! Check your rubber bushings on the trucks too, as they may no longer be usable if it's been sitting for a while. They help your trucks to turn left/right, so they are also important. The actual wheels/board/trucks shouldn't be too affected by time as long as they were kept in a good environment. I highly recommend bones bushings [LINK] and bearings [LINK], they're kind of the industry standard, and don't break the bank. You can find them in just about any skate shop in person or online.