Fatal Error in Woocommerce

There is a Fatal error in my website since last morning,I cannot access my WordPress dashboard,when I login this fatal error dislpays? Please tell me the soultion without losing data..! The error is:

Fatal error: Uncaught Error: Call to undefined function wp_timezone() in /home/n6cafc5/public_html/wp-includes/formatting.php:3510 Stack trace: #0 /home/n6cafc5/public_html/wp-content/plugins/woocommerce/includes/abstracts/abstract-wc-data.php(783): get_gmt_from_date(‘2019-09-05 09:3…’) #1 /home/n6cafc5/public_html/wp-content/plugins/woocommerce/includes/class-wc-customer.php(779): WC_Data->set_date_prop(‘date_created’, ‘2019-09-05 09:3…’) #2 /home/n6cafc5/public_html/wp-content/plugins/woocommerce/includes/abstracts/abstract-wc-data.php(668): WC_Customer->set_date_created(‘2019-09-05 09:3…’) #3 /home/n6cafc5/public_html/wp-content/plugins/woocommerce/includes/data-stores/class-wc-customer-data-store.php(170): WC_Data->set_props(Array) #4 /home/n6cafc5/public_html/wp-content/plugins/woocommerce/includes/class-wc-data-store.php(159): WC_Customer_Data_Store->read(Object(WC_Customer)) #5 /home/n6cafc5/public_html/wp-content/plugins/woocommerce/includes/class-wc-customer.php(104): WC_Data_Store->read(Object(WC_Customer) in /home/n6cafc5/public_html/wp-includes/formatting.php on line 3510
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