Barren wasteland?

That's generally indicative of a poor inet connection. The game loads but everything else it pulls from the servers (Pokémon, Pokestops, gyms), so if your connection is spotty you can get stuck with a blank slate, so to speak.

Most likely you just need to get a stable connection and you should be ok. The other possibility is that your local servers are overloaded, but I haven't personally seen that issue for some time.

Go under your Application Manager and clear the cache on Pokemon Go seems to work usually.

Otherwise, you have to uninstall/reinstall

It happened to me too at more or less same hours as your question. But now it works fine :)