I was driving my car in standing water. We changed the starter and now that it starts it's knocking, what now?

Question

Pontiac Grand Prix, 1999, SE edition

Answer 1

i would suspect that water was injested by the engine, as liquids are not compressable and a hydraulic lock has occured. the condition of connecting rods [bent] and big end bearings[mashed flat] are the most likely ruined items.
at this age it may be wisest to purchase a low milage engine from a junkyard and install that as opposed to patching up what is left of yours

Answer 2

water in the gas and or oil

Answer 3

a new engine.