Q.Growing a grape vine in a container
I was given a grape vine last year. The growth looked good, it had three small bunches of grapes. It grew up the trellis very well. I followed the instructions about the first frost and cut it back to the two buds. This year it started to produce leaves followed by small bunches of grapes. Suddenly the leaves started to wilt and die, then the small bunches of grapes did the same. Now I have a completely bare stem, no sign of any new leaves and obviously no sign of any grapes. I have removed it from the pot it was in (16inch diameter pot) and put it in a smaller pot after putting rooting compound on the roots just to see what, if anything, will happen. Any help/advice would be appreciated.

With no green growth, only woody stems, it appears your grapevine died off.
https://www.gardeningknowhow.com/edible/fruits/grapes/container-grown-grapes.htm