Yeah, but what you say, is that Vector2 is better to use than Point in games? Well I fixed it. And here is my new code. Thanks alot for the help guys! Realy amazing community here on gamedev!
if (target.Position.Y < 0)
{
Vector2 vv;
Vector2 vp;
vv = target.Velocity;
vv.Y *= -1;
target.Velocity = vv;
vp = target.Position;
vp.Y = 0;
target.Position = vp;
}
else if (target.Position.Y > SCREEN_HEIGHT - target.Origin.Y)
{
Vector2 v2v;
Vector2 v2p;
v2v = target.Velocity;
v2v.Y *= -1;
target.Velocity = v2v;
v2p = target.Position;
v2p.Y = SCREEN_HEIGHT - target.Origin.Y;
target.Position = v2p;
}