Retrieve deleted photos and videos

Hi, I would like to retrieve deleted videos from my iPhone 4s. I had videos on their which I might need for a lawsuit. Is that something I could be helped with? I had got a new phone about 4 months ago with my apple care protection and when I went into the store they took my old phone and gave me a new one. While I was waiting at the store, I had spend $20 to back up my phone because it didn't have enough memory remaining to store my data so I went ahead and purchased the plan. Please let me know, thanks.