If you still need it, you can flip them with this method:
private SpriteRenderer mySpriteRenderer;
void Awake()
{
mySpriteRenderer = GetComponent<SpriteRenderer>();
}
if (Input.GetKeyDown("A"))
{
mySpriteRenderer.flipX = false;
}
else if (Input.GetKeyDown("D"))
{
mySpriteRenderer.flipX = true;
}