Is to check the 3D glasses. Some are active and need a battery change. Passive? Then you check your 3D source, that is you play a title that you know worked before.
If resets fail to help, you call Sony's support.
I have a sony kdl43w800c tv and the 3d was working perfectly. Suddenly, now, I see weird ghost colours and lines only (no picture) when I turn on 3d.
The 2d works perfectly.