How can I get the bumblebees back?

Not sure what your question is. The big fuzzy yellow and black bumble bees do not sting you. Leave them alone. They are big and clumsy just minding their own business.

Be nice to bees. Without them we wouldn't have food. Put some diluted honey where you want them to go. Or buy buy some flowers already in bloom to attract them. They especially like yarrow.

There are flowers that attract both bees and hummingbirds. Try looking at garden stores or online for plants that attract bumblebees.

They may still be there but bumblebees like hot temperatures and sun. We found our colony would tend to "hibernate" when the temperatures cooled but we would see them again once it would get hot.