2005 cavalier

My son and daughter in-law were drinking
and drove through deep water and car
stalled. They were stalled in the water for an
hour or so then we had cavalier towed. After
a few days of sitting I tried to start the car.
The inside lights etc flickered and the door
open buzzer sounded on an off but the
engine never made a sound. It's been sitting
without a battery for about a year. I'm about
to try to get it running, again. Any
suggestions? TIA!