There are number of free and commercial tools available to test accessibility of web sites. Following is a list of tools that are popular and easy to use:
Screen Readers:
(1) NVDA screen reader: http://www.nvaccess.org
(2) ChromeVox (Chrome extension): http://www.chromevox.com
(3) WebAnywhere: http://webanywhere.cs.washington.edu/beta
(4) JAWS : http://www.freedomscientific.com/Products/Blindness/JAWS (Free Trial Available)
Tools to verify website accessibility:
(1) WAVE: http://wave.webaim.org. More details: https://www.testing-excellence.com/wave/
(2) TAW: http://www.tawdis.net