It's kind of hard to diagnose your problem without knowing how much water and fertilizer the plants were getting, and what the weather in your area has been like lately.Off the top of my head my first guess for the plants wilting is not enough water and hot temperatures,and then overfertilizing and if those don't seem to be the cause I would then consider a pest problem. I do grow basil and tomatoes and know they both need a good amount of water.