but why do I have stopped working version 3.4?

Using Sweet Home 3D with Java Web Start should automatically update it. But if you use the installer version, there's no reason that it stopped working.

I had to remove it! and, together with the program removes the entire library of textures, furniture, which I downloaded. I was very upset ....((

Uninstalling the program doesn't remove installed libraries. You must have removed some files yourself, or maybe you use some kind of program cleaner which removed the libraries.