Texture Pack Issue

So I log on to Minecraft Launcher right? Then I press play so I wait about for 5 mins on the Mojang screen then bam it launches me back to Minecraft Launcher and it says this:
The game crashed whilst initializing game
The game crashed whilst initializing game
Error: net.minecraft.client.renderer.StitcherException: Unable to fit: minecraft:blocks/lava_flow, size: 32x32, atlas: 0x0, atlasMax: -1x-1 - Maybe try a lower resolution resourcepack?
and I just don't know what to do, Minecraft was my favorite game please someone help me