Redesign my T-Shirt Design in AI

I need to update the existing design of my T-Shirt in Adobe Illustrator (.AI) format. Although I already have the design, I am not able to convert it into .ai, so I need someone with the skills to do that. The file size should be feasible, and could range from small (up to 8x10 inches) to large (up to 24x36 inches), depending on the details. I do not have a preferred colour palette and the design should remain unaltered.