how to rebuild sitemap in wordpress?

Sorry if my question was stupid or very basic but please someone tell me how to rebuild or reset the sitemap. currently i m using wordpress plugin for generating sitemap

http://ift.tt/1hEg0To

now i m looking to rebuild or reset the sitemap because many links giving 404 not found error. I found link called debug function in the plugin setting page. when clicking the click it loaded page and at the end of page shown button called rebuild or return so i clicked rebuild but there was no change in sitemap.

please someone help me to solve this issue

via Chebli Mohamed