Im trying to play gta v and says play game but once launched it says unreadable?

There must be something wrong with the disc. Try wetting something a tiny bit (I like to use a little corner of my t-shirt) and rub all around the disc. Then dry it off with the dry part of your shirt and try it again. If this doesn't work, there's another thing you can do. Borrow somebody else's GTA V disc and put it into your xbox. When the disc is in make sure you are on the dashboard. Now go to 'Games', then 'My Games' and scroll over GTA V without pressing it. If you press X, it should go to details and there should be a little tab that says install on it. Press install and wait for the game to finish installing. It is important you borrow a working disc from somewhere else whilst installing otherwise you won't be able to do the install. Now after the install is done take out the working disc and put in yours which doesn't work. As long as the xbox recognises that the disc is GTA V then it should allow you to play the game, even if the disc doesn't work. Although the game is installed, you will still have to insert your disc to play it but you won't need a working disc anymore. Hope this has helped.