Offline play only? No multiplayer?

Put the summary of the bug you're having here

What I expected to happen was...:
For a while, my launcher would show "Log out" and "Play" buttons on the bottom of the screen, but now it never shows the play button.

What actually happened was...:
the play button disappeared, It has been replaced by "Play offline". My "service status" area of the launcher says online, no problems detected.

Steps to Reproduce:
1. I do not know how it happened, or how to re-do it. I just can't play online.

Thanks!