Thanks for writing. How's the weather where you are? Coconut Sorbet viola is a cool-season plant and it often starts to falter once temperatures heat up --- so if it's staying more than 80F or so, that could be it.
If your temperatures are still nice and mild, then it makes me wonder about fertilizing. Have you fed your violas since you did a week and a half ago? If so, the problem could actually be too much fertilizer. When this happens, the excess fertilizer hurts the roots. Since the roots absorb moisture and nutrients for the plants, the plants start to wilt because they don't have enough roots to support all the leaves and flowers.
How moist is the soil? If it's staying wet, the problem could also be that the roots are drowning. The same kind of thing happens --- the roots die and the plant wilts. If this happens, letting the soil dry out a little more between waterings should help.
---Justin, Senior Garden Editor, BHG.com