If a bat gets into your home, it's usually a lost young one that's scared and looking for a way out. Even if it's sick, it usually only bites to protect itself if you try to touch it.
To get the bat out, don't panic or run away. If you do, the bat might hide and you won't know if it's gone. Stay calm and watch the bat. Close doors to other rooms and open a window or door to the outside. Keep an eye out to make sure the bat flies out.
You can also wait for the bat to land. Carefully go up to it with a container about the size of a coffee can, or shoe box. Clear plastic is best. Gently cover the bat with the container and slide a piece of cardboard underneath to trap it.
If you think someone in your home or a pet might have been bitten, take the bat to your local health department to check for rabies. Most of the time, the bat will not have rabies, but it's good to be sure. To let the bat go, just open the container outside, and it will fly away happily, or place the container near a tree for the bat to climb up and out when it's ready.
If it looks like the bat is injured, contact a local wildlife rehabilitation professional. Do not offer the bat food or water. Leave it in a container (with air holes) in a quiet spot until a professional can be reached.