Is 'sorry' an useful word?

Have you ever feel like you are so in wrong in a situation? And no matter what, you still clearly know that you are the one who did terribly wrong and there's no way you can justify yourself out. And indeed you are the one who should be responsible for the whole situation. What would you do next?

Since young, we were taught to admit our mistake and apologize with the word 'sorry' if we ever did anything wrong. As we grow older and older, this virtue remains and we always apologize immediately if we found ourselves in wrong, mmm...just like if we accidentally knock someone in a crowded place, or if we step on someone's toe unintentionally, etc. I feel that to say sorry to someone we don't really know is always easier. And it doesn't take so much courage for it.

But then, when the same thing comes to people around, guess things wouldn't be the same, and seems like it is always harder to bring the 'sorry' word out from mouth. I feel I'm always such a person, tend to keep sorry to myself most of the time, sometimes, even try to run away from the situation. It's not that I find sorry a shameful word to say nor feeling that I wasn't in wrong or trying to justify for what I had done. I feel the guilt, I know I'm in wrong. But, sometimes, I do wonder also. Is sorry an useful word? Will thing change just because of a few 'sorry' words?

I'm not trying to say apologizing brings no benefit, but sometimes, I feel despite how many times of sorry one side is willing to say, certain thing when done, will always remain irreversible and nothing will change because of the 'sorry'. It's like for instance, what if I hit a person's car, then I say sorry, will it un-hit the car? And what if I shouted too loud when watching WC and woke everyone in the house up, then I say sorry, will it make everyone continue with their sleep again or compensate for the sleep time they lost? And what if I borrowed something from my friend and lost it eventually, then I say sorry, will I recover the lost piece again? And what if I put the whole kitchen in mess and I went out right after that, and my housemate got to clear up the whole mess for me, then I say sorry to them after that, will it make any different? And of course, I know if I can be less careless and more careful, all these are avoidable. Those were indeed my mistake. I'm sorry to ppl concerned with the situations mentioned above as those were my mistakes and I don't remember saying sorry to you all.

But, what if 'bigger' things happen? Is sorry really an effective word? And if one does say sorry and the other person say something like 'it's ok... I accept your sorry' or something equivalent to that, does it really mean the mistake wouldn't be taken to heart? Or is 'sorry' just a word to help ease one's (who apologizes) guilt-ridden heart?