Migration to localhost causes 404 errors I'm trying to copy my site on my computer.

I've successfully downloaded and setup all the things. My site localhost URL is http://localhost/rich/ and when I run this URL, it opens my site homepage perfectly; after this, any clickable link gives me a 404 error page.

When I run this URL http://localhost/rich/user on my localhost, it gives me the following error:


  Not Found
  
  The requested URL /index.php was not found on this server.


Can anyone tell me what is wrong? What should I do it to fix it?
Recently had simmilar issue. If your Drupal site were set up with clean url-s , you might want to change 

#   RewriteBase /


in .htaccess file


Try comment it out. 
If commented, try to uncomment it.
Try to add subdirectory in that declaration, if drupal is installed
under any


Of course, check mod_rewrite as was suggested by optimusprime619