Returning the form in form_alter function I have a doubt that is, can i use return $form; in hook_form_alter function. When i used some callback function inside the form, its not calling to that particular function. Thatsy i confused whether the form is returning or not.
i tried this thing but its not calling to custom_form_reset function

function cap_academy_contactus_form_alter(&amp;$form, &amp;$form_state, $form_id) {
       if ($form_id == 'webform_client_form_860'){
        $form['actions']['reset'] = array(
          '#type' =&gt; 'submit',
          '#value' =&gt; t('Reset fields'),
          '#submit' =&gt; array('contact_form_reset'),
          '#prefix' =&gt; '&lt;div class="contactform"&gt;',
                '#suffix' =&gt; '&lt;/div&gt;'   
        );
        return $form;
      }
    }

    function contact_form_reset($form, &amp;$form_state){
      $form_state['rebuild'] = FALSE;
    }
You can use it, sure. But it won't do anything. 

The $form is passed by reference, precisely so that it can be altered in-place. Core never does anything with the return value from form alters, so there isn't much point doing it.

Your code looks right, put a drupal_set_message/dpm in the submit handler to confirm whether it's actually being called or not, or whether it's your one-liner that's not doing what you're expecting.