Based on my experience, Avis doesn't notify you when your points are due to expire. I lost the points I had, too. I didn't bother to ask them about it. It was my mistake for not paying attention.
That said, it would have been difficult for me to use any points. I only do local or one-way rentals. The Avis office where I rented relocated to a different part of town. Instead of being in walking distance from home, it's now a bus/taxi ride. I can still walk to 4 other rental locations, which makes Avis no longer worth much to me.
I basically stopped using Avis because they moved...which lead to the inactivity. I'd definitely be more upset if those points were of more value to.
Hopefully, you can get your points back.