There are not many land plants that will not survive after being under water for 2 weeks.

I am sorry to say, the damaged lawn may have to be replaced after the water recedes. You can either dig plugs from the healthy grass and plant in the damaged area or purchase sod to plant.

I will warn you that there are many who will be looking for sod when the rain stops and flood water recede. Measure your area and order the sod as soon as the water recedes. One pellet covers 350 square feet if planted solid.

Check with your local emergency preparedness center to ask their opinion about when the water will recede and not flood again. Do not plant until you are sure no more flooding will occur.