Putting on texture pack

So i had the regular texture pack on, and i was confused because i had the Minecraft classic texture pack on, so i exited the game and tried to put it back and when i did it told me to buy it again (its free) over and over it won't let me use it, even the other texture packs i got won't let me use them, it will only let me use the default texture pack or the mario texture pack.