Getting my old Terminal back after uninstalling fish
The simplest way to get back your default .bash_profile might be to just create a new user on your Mac. Log in and copy the desired files to that user's shared/public folder. Then log in as you and copy them to the root of your profile folder.

The added bonus of this is that you now have a virgin, virtually untouched, user that you can use when troubleshooting your Mac. Unless you are short of disk space a new user profile is not that big and can be valuable in troubleshooting.