Not able to login in my site

I was unable to login to my site.
I check the logs file on host and find that
2016-06-25 10:12:34 Error 193.92.97.51 500 POST /wp-cron.php?doing_wp_cron=1466838754.0378670692443847656250 HTTP/1.0 WordPress/4.5.2; http://ygeia-enarmonisi.gr 429 Apache access
2016-06-25 10:12:36 Warning 193.92.97.51 mod_fcgid: stderr: PHP Fatal error: Uncaught Google_ServiceException: Error calling GET https://www.googleapis.com/plus/v1/people/117238022143360054706/activities/public?maxResults=5: (403) Daily Limit for Unauthenticated Use Exceeded. Continued use requires signup. in /var/www/vhosts/holistic-therapies.gr/ygeia-enarmonisi/wp-content/plugins/wpmu-dev-plusone/lib/external/google/io/Google_REST.php:67 Apache error
2016-06-25 10:12:36 Warning 193.92.97.51 mod_fcgid: stderr: Stack trace: Apache error
2016-06-25 10:12:36 Warning 193.92.97.51 mod_fcgid: stderr: #0 /var/www/vhosts/holistic-therapies.gr/ygeia-enarmonisi/wp-content/plugins/wpmu-dev-plusone/lib/external/google/io/Google_REST.php(37): Google_REST::decodeHttpResponse(Object(Google_HttpRequest)) Apache error
2016-06-25 10:12:36 Warning 193.92.97.51 mod_fcgid: stderr: #1 /var/www/vhosts/holistic-therapies.gr/ygeia-enarmonisi/wp-content/plugins/wpmu-dev-plusone/lib/external/google/service/Google_ServiceResource.php(177): Google_REST::execute(Object(Google_HttpRequest)) Apache error
2016-06-25 10:12:36 Warning 193.92.97.51 mod_fcgid: stderr: #2 /var/www/vhosts/holistic-therapies.gr/ygeia-enarmonisi/wp-content/plugins/wpmu-dev-plusone/lib/class_wdgpo_google_auth.php(139): Google_ServiceResource->__call('list', Array) Apache error
2016-06-25 10:12:36 Warning 193.92.97.51 mod_fcgid: stderr: #3 /var/www/vhosts/holistic-therapies.gr/ygeia-enarmonisi/wp-con in /var/www/vhosts/holistic-therapies.gr/ygeia-enarmonisi/wp-content/plugins/wpmu-dev-plusone/lib/external/google/io/Google_REST.php on line 67 Apache error
2016-06-25 10:12:38 Error 2.86.102.23 500 GET /wp-admin/ HTTP/1.1
I will reset plugins to get in.
Thanks a lot