It is both true that you can't do anything to make up for the wrong that you have done, because sin is sin and once it has been committed it cannot be undone, and that you can do things to make up for the wrong that you have done in that it is important to do the right thing after you have sinned (to make things right).That's true. Any given person, even unbelievers, can do good things, and they can even serve others, but those things won't save them. Those things won't make up for the wrong they have done.
Shalom.
Jacob