Firstly, have a look to see if there are any green stems and if there are it is telling you that the plant is still alive and may be encouraged to grow again.
In these cases, clean the plant up, remove any suckers, strip back dead leaves and trim off the dead wood. If a grafted plant, remove the leaves of the root stock. In cold areas, do a small tidy and trim, not all the way back to the green yet. In warmer climates you can trim back to the green. Either way the bed will look a lot tidier, and you will feel as if you are winning rather than not!
While you are there, weed, top up the soil with planting mix and mulch to give them half a chance at going for another season.
You can feed them, but only a diluted amount, as you don’t want them to take off!
You will then need to cover the plant with a small hot house or like and then just watch and maintain through winter. However, we have an eggplant in the garden at the moment that is completely surrounded by parsley, and I am leaving all that as it is for now just to see if that is enough to keep the eggplant warm through the winter. I might as well give it a try as it has all fallen together like that, as you can see in the pic above.
If you see mildew or mites on the plant, that like humid environments, you will need to create more airflow, the easiest way being to just open up the hothouse or like during appropriate days.
Now there is no guarantee that the plants will come back to life, but why not give it a go and see if you can encourage another season out of them. Just a nice and easy experiment
Enjoy!
Peter