I think they will eventually come back.
Keep them watered.
A good idea for hanging baskets are the slow release fertilizer granules which release plant food slowly over time.

Sounds like a classic case of overwatering not fertilizer. You should let your baskets dry between waterings. There are not too many plants that like constant moisture. It can look dry and yet have lots of moisture below. If you are unsure then stick your finger in the soil. If it feels wet half way down don't water.

More plants are killed from overwatering than lack of water.

Let your plants dry out completely and they may or may not come back.

thanks for the info. When I bought the baskets the nursery owner said to use miracle grow every watering as that's what she does(?) I think it's a combination of too much fertilizer and too wet (not much sun to dry them up). I'll dry out and cut back on fertilizer - every 10 days okay? I'll check my printed instructions this time!

If you fertilize at every watering, you have to use a dilute solution of one-tenth the recommended rate. This is what I do with my orchids and houseplants.

For outdoor plants and vegetables, I fertilize only once a week or so at full strength.

soaking wet? I think it's both. Overwatered and over fertilized. BTW what's the drainage like in this container?