Hi @harshita_chouhan
Seems like file is hidden at your end !!
anyways are you installing this on wamp server on windows ?
Refer this link - https://community.magento.com/t5/Installing-Magento-2-x/Magento-2-Localhost-Admin-url-returning-404-...
Also for .htaccess - https://magento.stackexchange.com/questions/89125/how-to-fix-magento-2-2-0-0-rc-admin-page-not-found...
