Probably too late to replant carrots. Just do what you can to protect them.

I plant carrots pretty much all year long except when the ground is frozen.

I think this is one of those cases where diatomaceous earth is actually the best solution.

In general rolly polly/pill bugs eat primarily vegetation that has somewhat started to decay so there may be another culprit with your carrot problem.

Nothing is bothering mine thankfully but the damn cabbage worms are killing my Kale and Collards. Bought some floating row cover for the next crop that I'll plant in August.