@AceRagz basically laid it all down.
Even more so, sometimes the person you had a fallen out with has moved on. They just probably don't care anymore, probably will have forgotten about the argument and/or you, and you lingering around or continuing to try and get in touch just won't affect them. As harsh as that is, and not saying that person has done this completely, it's true sometimes. And it's not even in bad intentions -- some people are just firm in their decisions and move on.
It's one of those things that happens in life. We can try to ask ourselves and say "well, what if I said something different", but we just can't do that. We can't control the past, but we can control our present.
Disregarding the quarrel -- do you still want to work on it at all? Does a part of you still like the content? If so, I feel it would help to take a break from it but not outright quit. There's no shame in putting the work on the backburner, especially if the argument is still fresh in your mind. But don't let it take away something that you really do enjoy doing.
Sometimes, you can't get the closure you desire, and while that's not always ok, it is something we have to acknowledge while still knowing the things we can control. This could be a part of your own closure, of taking a break and assessing your feelings. After all, self-care is important.