iTunes locked in a song

Problem solved.

As strange it may sound. I just did a few restarts - didn't work.

I let the phone simply sit in airplane mode overnight, basically letting it sleep.

Before you hit your forehead with hour flat hand in an understandable motion : this worked. When I opened iTunes I quickly went to Playlists and was able to open one and start a song.

Correction: the buttons work. I can click them, but within two seconds iTunes flashes off the screen into the background.

It's like a diver that has lead on his legs and cannot keep on the surface for more than two seconds.

Save my iTunes from drowning!

Nobody has an idea what happened here? It's not really crashing, just always withdrawing from access and sliding into the background. I can't listen to music on my iPhone any more.