ReflectionMedia

This plugin allows sorting of posts alphabetically, by Post Title (ascending or descending) or Post Date (ascending or descending), customizable for each category.

WP Post Sorting

This plugin allows sorting of posts alphabetically, customizable for each category.

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This plugin adds a drop-down list with the ability to sort your blog posts: 
* sort by title; 
* sort by date (newest first); 
* sort by date (oldest first); 
* sort by date last modified.
Paste the following code in the templates ‘index.php’, ‘archive.php’, ‘category.php’ or/and ‘author.php’ etc.:
This tag must be before The Loop. For more information go to the “Installation”.

WP Sort Posts

Add the ability to sort the posts in the archives of your blog!

WP Post Sorting vs WP Sort Posts