wordpress wp_mail throws error: could not instantiate mail function - wordpress

Question

I have two forms in my website. Both were working fine. but suddenly now they are not working. Emails are not going from both the forms.
// This function gets called when user clicks on submit button
<script type="text/javascript">
var $ = jQuery;
function sendMessage(){
var name = $('[name="name"]').val();
var email = $('[name="email"]').val();
var phone = $('[name="phone"]').val();
var message = $('[name="message"]').val();
var filter = /^[7-9][0-9]{9}$/;
var emailReg = /^([\w-\.]+#([\w-]+\.)+[\w-]{2,4})?$/;
if(name == '')
{
$('.name-error').show();
}
else
{
$('.name-error').hide();
}
if(email == '')
{
$('.email-error').show();
}
else
{
$('.email-error').hide();
}
if(phone == '')
{
$('.phone-error').show();
}
else
{
$('.phone-error').hide();
}
if(message == '')
{
$('.message-error').show();
}
else
{
$('.message-error').hide();
}
if(name != '' && email != '' && phone != '' && message != ''){
if(emailReg.test(email)){
if(filter.test(phone)){
var data = {
url: '<?php echo admin_url('admin-ajax.php');?>',
type: 'POST',
action: 'send_mails',
formdata: $("#contact").serialize()
};
var myRequest = jQuery.post(data.url, data, function(response){
console.log(response)
});
myRequest.done(function(){
$('#msg').html("<p class='msg' style='background-color:#dff0d8; border-color: #d6e9c6; color:#3c763d; padding:10px; border-radius:4px;'>The Email has been sent successfully!</p>").fadeIn('slow');
$('#msg').delay(5000).fadeOut('slow');
});
$("#contact").trigger("reset");
$('#msg').html("<p class='msg' style='background-color:#dff0d8; border-color: #d6e9c6; color:#3c763d; padding:10px; border-radius:4px;'>The Email has been sent successfully!</p>").fadeIn('slow');
$('#msg').delay(5000).fadeOut('slow');
}
else
{
alert("Provide valid mobile number");
}
}
else
{
alert("Provide valid Email Id");
}
}
else
{
// alert("Kindly enter all the details");
return false;
}
}
</script>
This is function from functions.php file.
function send_mails()
{
$formData = $_POST['formdata'];
$data = array();
parse_str($formData, $data);
$name = $data['name'];
$email = $data['email'];
$phone = $data['phone'];
$message = $data['message'];
$msg = "A new enquiry has been posted on the website\n";
$msg.= "Name: ".$name."\n";
$msg.= "Email: ".$email."\n";
$msg.= "Phone: ".$phone."\n";
$msg.= "Message: ".$message."\n";
$headers = array('Content-Type: text/html; charset=UTF-8');
//echo $msg;
$admin_email = get_option( 'admin_email' );
// print_r($admin_email);
$res = wp_mail('email',"Enquiry",$msg,$headers);
if($res)
{
echo "Mail has been sent";
}
else
{
echo "Could not send mail";
debug_wpmail($res);
}
die();
}
add_action('wp_ajax_send_mails', 'send_mails');
add_action('wp_ajax_nopriv_send_mails', 'send_mails');
debug_wpmail returns the error "Could not instantiate mail function". I did not find anything on google.
if ( ! function_exists('debug_wpmail') ) :
function debug_wpmail( $result = false ) {
if ( $result )
return;
global $ts_mail_errors, $phpmailer;
if ( ! isset($ts_mail_errors) )
$ts_mail_errors = array();
if ( isset($phpmailer) )
$ts_mail_errors[] = $phpmailer->ErrorInfo;
print_r('<pre>');
print_r($ts_mail_errors);
print_r('</pre>');
}
endif;

Answer 1

Can you modify this part :
From
$res = wp_mail('email',"Enquiry",$msg,$headers);
To
$res = wp_mail($admin_email,'Enquiry',$msg,$headers);

Answer 2

This happens due to your site haven't been configured with email service provider like Google/SendGrid or SMTP Or It just goes removed. Example configuration can be found below: