After successfully opening and playing the 13w16a snapshot for the first time, I closed (so that it was no longer running) and reopened the launcher to find that I can no longer log in to play it. The drop down menu for the version (where you would be able to select a .jar) is completely empty, and so no version is selected, and the "play" button is in grey, and I cannot use it.

It seems that no one else has reported such a bug (if this even is a bug), or I haven't been able to find it at all, so I am sorry if this is a near duplicate.

*I have bought a copy of Minecraft, from the official Minecraft site, and am owner of a premium account; I doubt this has anything to do with it
*Password is automatically filled in when launcher is opened. I also doubt this has anything to do with it

If someone could help in any way, I would appreciate it. I'm sorry if this is a duplicate, and also if this is overly detailed for the issue.