CiviCRM Dashboard and Menus disappear after upgrade and GoCardless extension disabling
This is because your cms.root doesn't match properly with civicrm.root variable and you might be using variables in Resource url for 'CiviCRM Resource URL'. 

You need to make sure paths are correct in your system


Check the Document root path in your apache or nginx config of site.
It should match exactly with the path of $civicrm_root and template_c path in settings.php


For some cases you add below two line at the end of the file you will need to change 

$civicrm_setting['URL Preferences']['userFrameworkResourceURL'] = CIVICRM_UF_BASEURL . 'sites/all/modules/civicrm/';                                                                                                     
$civicrm_paths['civicrm.root']['url'] = CIVICRM_UF_BASEURL . 'sites/all/modules/civicrm/';