Minecraft refuses to load

I am experiencing problems with Minecraft, both the game and the launcher. The launcher doesn't recognize it's connected to the internet until I press the refresh button, but my brother, which I share the computer with, gets refreshed automatically. In the game, loading the game code is fine, but loading my only world isn't. It just takes forever to load the world even though the screen says 100%. When it finally loads, Java crashes. My three theories for the latter: 1. My dad's account was logged in when I was testing this, and whatever he has open is a RAM hog. 2. There is something wrong with the hardware that I can't see. 3. There is something wrong with the software.

This may not be related, but F11 no longer works on the launcher. 

Update: The log looks like the game attempted to load everything, but minecraft:block.smithing_table.use, a lot of game data, and also a lot of recipes weren't loading.