Please handle the bat as little as possible and minimize contact with humans and pets.
If a bat is trapped in your house open all windows and doors and try to usher it out using a towel.
If the bat is injured and cannot fly, wear thick gardening or leather gloves and using a towel placed over the bat, pick it up and transfer it to a ventilated box, Bats can slip through small spaces so be sure that the box is tightly closed and has small air holes, once contained, contact your local registered bat carer or wildlife rescue for advice on transporting the bat into care.
Once a bat is grounded it cannot easily take off again unless it climbs up a vertical structure - they cannot easily take off from the ground.