Grass is able to re orient itself and should recover. If it is actually laid down and stuck in the soil, it will take longer as the new blades will have to work their way out to grow upwards again. As he grass gets older it will be able to resist the damage from future rains. Depending on how old it is, you could consider using a leaf rake and very lightly going over the lawn to dislodge any grass blades adhering to the soil.