renp

A simple WordPress plugin which adds a “scroll to top” button to the bottom corner of the page if the page has been scrolled down. It is compatible with all major browsers and should work with all themes, including 
responsive and high resolution themes.
It is possible to configure the plugin in the admin area for choosing between light or dark colour schemes and size of the button as well.
If your theme doesn’t already contain this feature, you can simply add it by means of this plugin.

Scroll to Top Button

Displays a button in the bottom right corner for smooth scrolling to the top of the page.

Dostogir

This plugin will add a nice scroll to top icon on a scrollable page and will add a nice colourful browser scroll on chrome.

Smooth-scroll-to-top

Scroll to top with nice jquery scroll effect and get a nice browser slider

Scroll to Top Button vs Smooth-scroll-to-top