I own a 2012 Camry but it has not been run for about two years, and now it wont start. Is the hybrid battery at risk?

Define "won't start". Is it cranking over and over but not firing up? Or is it just dead. Like it won't crank over due to a totally spent battery?

Your battery should be fine. If not, I believe it's covered under warranty. Here is an article from Popular Mechanics........................ All batteries wear out over time, but several factors influence when that happens. Battery chemistry, the number of charge and discharge cycles, temperature extremes, even humidity. Your Prius carries a 10-year, 150,000-mile warranty on the hybrid battery. You'll notice two things when it's time for a new power pack: The engine will run almost constantly, even under light acceleration, and your fuel economy will drop off significantly. The good news is the car will still run with a bum battery, but a new one should keep your car running like new for years. Retail price for a new hybrid battery is $2589; with labor, it should be less than $3500 total. You may have to pay to dispose of the old battery too. It's a big hit to the wallet for a single repair, but still cheaper than a new car.

I seem to recall there is also a small 12 volt battery which needs to be charged to at least 12 volts in order to activate a relay thus allowing the Hybrid battery to start this vehicle. You might consider putting a SLOW charge(no more than 2 amps) for about 24 hours on the 12v battery....then attempt a restart.