when click on category to get latest post in that category

Hello coders,
title looks simple, somebody will say add showpost=1 but its not so simple. When u click on category you call category.php and in that template previous_post_link doesn’t work. SO i want to go directly to single.php that hold this category latest post and in sidebar to add link to show me all posts from this category if i want to.
If this can work i can add also in sidebar next/previous to go thru posts of current category and i will add link to see all posts lists if i want to.

I hope there is an answer, also whant t pay somebody if its too dificult to do this.

Thanks