I cant play many games because I dont have vertex shader. Can I somehow deactivate it in game that I could play that game without it

no. even if you could deactivate it in the game engine, the menus would probably use it, so it wouldn't work. You could buy a cheap GPU for a very low price that would allow you to play simple games.

Ex.: Ge-Force FX5500 128Mb Pix.Shader 2 ; Vertex Shader 2 ! (OpenGL 2)