Why am I always "sneaking"?
Solution 1:
This happened to me last night. If you use a crafting table which places your character in third-person view, such as an anvil, your character will automatically go out of sneak mode. Then, just to be safe, go in and out of sneak mode a few times for the game to "readjust" itself, and everything should be fine.
The problem seems that the sneak toggling action is stuck; there is no way to manually trigger the switching of sneaking on/off. Remapping the key will not work since the "toggle sneak on/off" action will not be triggered. Instead, you need to "force" the game into removing your sneaking state. Certain actions do this, the most obvious and easiest is to use a crafting table. Using a crafting table will force certain state-based variables on your character, such as the view (which gets set to 3rd person) and the sneak mode (which gets set to "sneak off"). Therefore, no matter what your sneaking state is, using a crafting table (those who force you to go in 3rd person view) will also reset your sneaking state to be off, taking you out of sneak.
Once you are out of sneak, you will notice that pressing sneak will still not do anything, and if I recall your view will still be lowered as if you were in sneak. However, pressing sneak a second time will effectively reset all action states, making everything better.
I hope this helps!
Solution 2:
The real answer could not be easier:
Find a chair and sit down. Sneak is immediately toggled off.