It depends a bit on what type of hellebore we are talking about.....do you have a tag for it?

If it is an x hybridus, you should be seeing some signs of this season's growth by now. In my area, these are in full bloom now and and new leaves are starting push out of the soil surface. If you see no signs of growth at all, I'd be guessing that is not a very good sign and the plant could be dead. The good news is these types of hellebores tend to be rather tough plants and can take some neglect and abuse and still come back and thrive, so I wouldn't necessarily give up hope completely.

If something other than a xhybridus, I'd also not hold out much hope. These other types of hybrids tend to be much more fully evergreen and leaves that look fully dead generally mean the plant is dead also.

I would also recommend that you plant your hellebores in the ground as soon as you are able. While they will tolerate some time in a container, they really do not thrive in that environment long term. Going forward, most established hellebores are pretty drought tolerant but allowing a container planted one to dry out completely for any significant length of time is pushing the limit.