Don't ask how it happened, but my Seiko battery-powered watch spent a rainy day lying on my driveway. Now it doesn't run, of course. I have not tried to open it, because I don't know what I am doing, but I am trying to let the moisture which I imagine is trapped inside dry out.
Is there any chance that it will work again? I assume it will need a new battery, but I don't want to bother paying anyone to look at it if it is just dead dead dead. I don't know what water DOES to ruin a watch.
Provided it hasn't been wet long enough for any corrosion to set in, it should work again.
Take the back off and leave it in a warm, dry, dust-free place for a day or so to allow it to dry out thoroughly, then try a new battery.