Runaway Ralph by Beverly Cleary

Runaway Ralph is also one of my favorite books. It's about a mouse that lives in a hotel and he runs away because his little cousins and brothers and sisters and relatives are trying to get his motorcycle, and they actually loosen a certain part of it, so Ralph went to school with his friend. And at school, he feels lonely. Especially on Sundays and Saturdays. There's no mice to play with, it's too clean for mice. I can't tell you the end.

Runaway Ralph is a book and it was also made into a movie. You can get it on Amazon.com
Runaway Ralph