What kind of critter? Is this a houseplant or something planted in the ground outside? It makes a difference. It may just take some time if it is in the ground. If it is a houseplant, it could be root fungus. Luciee (;^)
I agree, some more details would be helpful. Pictures too if you have them. In some cases the plant will continue to look worse and worse even after you eliminate the problem because damage was done to the leaves already and they can't recover, so they eventually turn brown and die. But they often don't get to the brown & dying stage until after you've fixed the problem, so it looks like the problem is continuing to get worse when in reality that's not the case. I probably wouldn't cut it back yet until it becomes clear that entire branches of the plant are dead.
Moles can damage roots as they dig tunnels in the area, but they don't eat plants so if your critter was actually eating the roots then it was probably a vole not a mole. In either case though, you will just need to sit back and be patient. Assuming the plant has a decent amount of roots left it should recover but it may take some time, and since the root system right now may be inadequate to supply all the top part of the plant with water and nutrients you may see some more leaves die before it starts to come back. The process it needs to go through is to first develop new roots to make up for the parts that are damaged, then once it's done that you will see new growth above the ground. I would treat it like a plant that was recently transplanted--don't fertilize until it recovers a bit, and if it's getting a decent amount of sun then you might consider rigging up some shade for it until its roots have time to recover. The one other thing you could try is SuperThrive--some people swear by it for helping transplants get going quickly. It may not do much but it can't hurt and could help. I don't know what you were hoping the vinegar would do but I can't think of any possible beneficial effect from it in this case.