Water and electronics are usually not a good mix. Most laser pointers are not sealed and should be kept dry.
You could try to open it up and let it air out. After it drys it _might_ start working again (depends on how clean the water was). Remove the end cap and take the batteries out. Remove the front protective cap as well (if it has one). Leave it in a dry environment and let it air out for a few days.
...and cross your fingers.
Good luck!