Theme mod: now post are any problem =(

I’m using WP 2.6 with “Several” theme…I’ve modified any “small” things: the biggest was remove posts from the index page. To read the posts I’ve insert an rss reader that open the single post: but doing this, there is a big problem. WP doesn’t open a single post but all, like the normal index page. Anyone can help me?
Thank u so much!!