Sprite Movement

I am trying to make my sprite move from left to right in an infinite loop

I can make my sprites move left then right.

But the maths becomes a bit confusing after the timer is reset.

It goes

left -1
right +1

then the 2nd time it comes the to left cycle the movement is already at +1 instead of 0 so the code doesnt work and the sprite stays in one position.

Can anybody help me?

the return function wasnt working properly

solved now :p