how can make the unity game object a sprite without using a plugin such as sprite manager and etc
i cant find any tutorial about this issue can anyone help me
You could use a plane to which you add the material of your texture. Rescale it properly and make a prefab out of it (for later use).
Make it face the camera, add a box collider (or else) for collision, put proper dimension. I would guess you are in 2D so sprites are on the same z-position so that collision occurs.
In order to minimize vertex count, you could create a simple plane with blender with a lower amount of triangles.