Returning my terminal to default

I have been using prolog in terminal, and now as soon as i open the terminal it immediately opens with prolog,meaning that I can't use the terminal normally.
Does it anyone know how i can return in to default?

Thanks

Check for the existence of a file called ".bashrc" or ".bash_profile" in your home directory. There will be hidden files, so to see them you will need to turn on the ability to see hidden files. One of these two files likely has a prolog startup command in it.