I downloaded a map and it crashed whilst loading multiple times. I deleted it and went onto my creative mode world, at that also crashed on startup multiple times. I don't know what to do.

I can't get a full stack of items from any interface, no matter what I try.

In creative, whenever I click an arrow at the top of the inventory, it exits me out of the interface.

I have to click and drag one item at a time in and out of chests. I can't shift-click anymore. Affects all game modes and all versions since 1.6.