Hi,
Try few basic troubleshooting steps:
1) Flushing any caching plugins you might be running, as well as server and/or browser caches.
2) Try Deactivate All Plugins Through cPanel
Login at cPanel, Under Files section, Go to File Manager.
Select Web Root (public_html/www) and click Go.
Expand the public_html folder, and navigate to the /wp-content/plugins folder.
Right click on the /wp-content/plugins folder and rename it like plugins.old. This will deactivate all of the plugins at once.
Now, reactivate plugins folder again by renaming back to plugins. This will allow you to access the WordPress Dashboard again.
3) Switch to Default WordPress Theme
If the plugin disabling doesn’t work for you, switch back to default twenty fifteen theme. Access to WordPress directory either through cPanel or FTP, Navigate to wp-content/themes, locate the theme folder you are using and rename it. WordPress will automatically fall back to the default theme.
Thanks,