If a flooded vehicle is still in tact, and the water hasn't reached the internal workings of the engine, it can be salvaged, if its done within a couple of days. The longer it sits, the worse the damage can turn out.
If it hasn't reached the oil, perfect.
Would be best to change the oil before it started up anyway.
You also want to make sure theres no water in the air intake ports/vents/filters.
If there is, get it sucked out and dried. Replace filters.
Once thats been done, start the engine. If it starts and runs ok, let it heat up for about 10 minutes, but don't drive it.
Once the engine has cooled off, then that means all the relevant parts of the engine have been dried out.
Now you have to see if any water got into your brake fluid, trans fluid, and engine coolant.
If they are clean, then fine. If not, then change them out.
As for the interior, that needs to be sucked dry with a wetdry vac ASAP. As best as you can get it.
Once thats been done, it needs to dry out completely.
When the interior is dried completely, then you can check the electronics, wires, cables, etc.
Clean everything with alcohol or an anti fungal cleaning solution. Alchol is cheaper as you can get it at the dollar store, but be warned, it can damage some interior finishes.
Once that has been done, you can go back and have the carpet and seats steam cleaned with liquid Lysol or some other high end, bacteria cleaning agent. This goes for the trunk as well, if you have one.
Also check the trunk for water puddles, as some vehicles have wheel wells under the trunk floor mat where the spare tire is.
You want to make sure that is completely dry as well.
The doors should be kept open while the drying is happening, as there should be drain holes in the bottom of the doors, so keeping them open will let the water drain.
Once your vehicle is dry and clean again, then you should be able to use it as normal again.