"Will there be classes tomorrow" is correct to ask if classes will be held or not. Numbers 1 and 4 are grammatically incorrect. Number 3 means something different from what you're asking. "Will classes be there tomorrow?" questions the location of the classes, not if they will happen or not. For example, if your teacher has been mentioning a class-visit to a local park, you could ask "Will classes be there [meaning the park] tomorrow".

Will there be classes tomorrow is the correct one to use.