engine won't turn over but all lights and gauges work

Daughter, granddaughter and I were traveling to Tennessee. Stopped at Rest Stop in Ohio. Turned car off and locked it. Came back out. Car would not start. Steering column was locked. All gauges worked but car would not even turn over. Son in law was traveling with us in other vehicle. Checked fuses, showed nothing blown. Finally got car started by hitting the starter. Continued our trip but did not shut the car off until we reached our destination. Car sat overnight and started the next morning. Would restart but only after sitting for hours. Have replaced the starter, issue not resolved yet. No codes are being thrown. Never had this issue before. Have had the recall done for the ignition switch and the electric power steering pump. We had severe flooding just before we took the car on the trip and I drove through some high water in a couple places on my way to work. Car had been ok up until then except for the transmission, gauges complaint that other people have mentioned. That happened in June. Car made a huge noise, shifted hard and all the gauges went crazy..Speedometer didn't work, car redlined and I couldn't get any speed out of it. My mechanic fixed it (not sure exactly what he did) and seemed to be ok until this issue of the not starting. Mechanic thus far has replaced the starter but issue has not been resolved. Haven't had any other issues and used to love my Cobalt..Now, not so much!!! I am on a fixed income and can't afford to replace my car just yet! My mechanic has not given up yet and we are exploring all complaints to track down this issue