I can't login to Minecraft online anymore, and it only gives me the option to go Offline even though I have really good Wi-Fi. Whenever I try to run a world, it crashes and gives me an error report.

Put the summary of the bug you're having here

What I expected to happen was...:
Minecraft should have ran properly and Online.

What actually happened was...:
Instead, Minecraft ran Offline and crashed every time I go into a world. It might just be my computer, though.

Steps to Reproduce:
1. Open Minecraft Launcher.
2. Run Offline.
3. Open a world.