If J.K. Rowling, Jerry Seinfeld, Madonna, Thomas Edison, and Walt Disney all found a way to bounce back from being fired, so can you...
Always keep in mind that being a victim of getting let go, is not uncommon and you are not alone. Be prepared with a simple and reasonable explanation. Keep your response concise and positive.
Ideally, the background should be clean and clutter-free. If you can't find a suitable place in your home, your local library, a coffee shop, etc, then sub in a blurred background, a solid color that flatters you, or a "professional one" like an office/library with books or the like. You don't want to choose something that screams for more attention than you - You are the focus and you don't want to distract the interviewer from your message.