(just a random person who came by)

Well, it depends actually. If you get a flood of comments, it is hard to reply to every comment.
Sometimes you even don't know what to say, other than thank you, and I personally do that in my A/N. If there are questions, I answer them in the A/N as well, so that every reader can see it.
Also, I have to agree with PkmnMaster1505. Not every person here has a lot of time on her/his hand, so replying to every single comment can be a huge hassle, especially when you are very busy. Then again sometimes I don't want to reply to every single comment.
It is not rude or anything like that and the most of my readers are totally okay with that (I asked them themselves).
It also doesn't mean that the author doesn't connect to their readers. Wallpsosts and private messages are there for that.

the reason why i don't reply is because i don't really know what to say but i really do try to reply to people

Your the only one that replies to me when i comment

People probably have better things to do other than reply to comments... (Geezus that was harsh..) Anyways I understand you though... Maybe they don't want to reply...

I feel you! Sometimes I get really sad when I get ignored ): many authors literally beg to get comments and then 'ignore' it. I'm glad you're one of the nice authors on here :D

I feel the same way. :O

I usually get a lot of comments or im just busy. But if you ask question or say something like its my birthday or suggest something i will answer^_^ i usually try my best to rply but its hard sometimes

That's actually the reason I don't really comment on other fictions besides yours. There's not many authors that bother replying.

I completely agree. Especially if I ask a question. Then I really feel ignored. Some authors don't reply to any of the comments. That makes no sense at all. I reply as much as I can.

I met so many people who don't reply to comments. I think they think it,is a hassle and don't know how to respond

I know that feel if i take the time to comment the least i expect it's that the author reply to my comment but there are many authors that don't reply and it's really annoying

I understand you, especially since I spend time commenting on a lot of stories that I read. And sometimes it's disheartening to see these comments ignored, especially when you write a lot and spend a lot more time than 'update soon' or 'this is good' type comments that some people like to give. It's even worse when you go out of the way to give constructive criticism and are ignored because the author doesn't want to be helped or doesn't care or just thinks you're wrong, even when you provide coherent and well thought out examples.

But as an author, I also understand that it is sometimes hard to reply to comments all the time. Sometimes I really have no idea what to say, so it's a struggle to find some words sometimes. However, I do my best to reply to comments, even if it takes longer than most since I'm usually busy doing other things. But I do try to reply to comments whenever I update, so even though it may take a week or three to reply, I do my best to reply to them.

But most of the time when an author doesn't attempt to reply to comments is because they don't really care about connecting with their readers. Or the author just has too many comments to reply to, so they just don't do it, because that takes a lot of time.