Maybe you have many categories. This extension can filter and sort product by categories.

Key Features:

1. Sort categories by name;
2. Filteres categories.

No Installation and core modification required, just upload the xml file in package to vqmod/xml directory.

Thanks for using this.

If you have same error or nothing show, don't forget, this just MOD, which maybe don't work correctly with another modifications.
I recommended use fully extension which you see below.
Other version:
Admin product filter

Gift the developer 1$