How to get paint off wood?

When I was younger I used to play in my wooden Wendy house and all the kids in my street used to write on the Walls inside it, I hated it when I was little so I painted over it, not very well seeing as I was only young. Now I'm older I'd love to look at what people wrote, is there a way to get the paint off and not damage the pen on the Walls?? Thank you