How to reset password in codeigniter?

<center><h3 class='flashMsg flashSuccess' style="color: green;"> <?=$this->session->flashdata('successmsg')?> </h3></center>
<!-- <form action="<?php echo base_url()?>admin/profile/change_password/<?php echo $this->session->userdata('adminid');?>" method="post" name="" class="">-->
<form action="<?php echo base_url()?>admin/profile/changePassword/<?php echo $this->session->userdata('adminid');?>" method="post" name="" class="">
<div class="row">
<div class="col-xl-4 col-lg-6 col-12 form-group">
<label>Old Password *</label>
<input type="password" <?php echo set_value('old_password'); ?> placeholder="Old Password" name="old_password" class="form-control">
<?php if(form_error('old_password')){echo "<span style='color:red'>".form_error('old_password')."</span>";} ?>
</div>

<div class="col-xl-4 col-lg-6 col-12 form-group">
<label>New Password *</label>
<input type="password" <?php echo set_value('new_password'); ?> placeholder="New Password" name="new_password" class="form-control">
<?php if(form_error('new_password')){echo "<span style='color:red'>".form_error('new_password')."</span>";} ?>
</div>


<div class="col-xl-4 col-lg-6 col-12 form-group">
<label>Confirm Password *</label>
<input type="password" <?php echo set_value('confirm_password'); ?> placeholder="Confirm Password" name="confirm_password" class="form-control">
<?php if(form_error('confirm_password')){echo "<span style='color:red'>".form_error('confirm_password')."</span>";} ?>
</div>





</div>


<div class="col-12 form-group mg-t-8">
<button type="submit" class="btn-fill-lg btn-gradient-yellow btn-hover-bluedark">Save</button>
<button type="reset" class="btn-fill-lg bg-blue-dark btn-hover-yellow">Reset</button>
</div>

</form>

<?php
defined('BASEPATH') OR exit('no direct script access allowed');
class Profile extends CI_Controller
{
public function __construct()
{
parent::__construct();
if(! $this->session->userdata('admin_id'))
{
redirect('admin/login');
}
/*
$loggedIn = $this->session->userdata('admin_id');
if(!$loggedIn)
{
redirect('admin/login');
}
*/

/*
if($this->session->userdata('username') == NULL ) {
redirect('admin/login');
}
*/
}
// ########################################################
public function index()
{
$data = array();
$data['title'] = "Admin Profile";
$this->load->view('admin/header',$data);
$this->load->view('admin/profile');
$this->load->view('admin/footer');
}

// ################################# Password Reset #################

public function change_password($id='')
{

$rules = array(
[
'field' => 'old_password',
'label' => 'Old Password',
'rules' => 'required',
],
[
'field' => 'new_password',
'label' => 'New Password',
'rules' => 'callback_valid_password',
],
[
'field' => 'confirm_password',
'label' => 'Confirm Password',
'rules' => 'matches[new_password]',
],
);
$this->form_validation->set_rules($rules);


if($this->form_validation->run()==FALSE)
{
$this->load->view('admin/header');
$this->load->view('admin/profile');
$this->load->view('admin/footer');
}
else
{
$data['oldpass'] = md5($this->input->post('old_password'));
$newpassword = md5($this->input->post('new_password'));

$userinfo = $this->Admin_model->reset_password_verify($id,$data);
if(!empty($userinfo)){
$data_array = array(
'id' => $id,
'password' => $newpassword

);

$updatedata = $this->Admin_model->password_reset($data_array);
$this->session->set_flashdata('successmsg', '<div class="alert alert-success" text-center"><h3>Your Password Successfully Updated !</h3></div>');
redirect('admin/profile');
}
else{
$this->session->set_flashdata('successmsg', '<div class="alert alert-success" text-center"><h3>Plase Check Your Old Password</h3></div>');
redirect('admin/profile');
}

}



}



//Create strong password
public function valid_password($password = '')
{
$password = trim($password);

$regex_lowercase = '/[a-z]/';
$regex_uppercase = '/[A-Z]/';
$regex_number = '/[0-9]/';
$regex_special = '/[!@#$%^&*()\-_=+{};:,<.>ยง~]/';

if (empty($password))
{
$this->form_validation->set_message('valid_password', 'The {field} field is required.');

return FALSE;
}

if (preg_match_all($regex_lowercase, $password) < 1)
{
$this->form_validation->set_message('valid_password', 'The {field} field must be at least one lowercase letter.');

return FALSE;
}

if (preg_match_all($regex_uppercase, $password) < 1)
{
$this->form_validation->set_message('valid_password', 'The {field} field must be at least one uppercase letter.');

return FALSE;
}

if (preg_match_all($regex_number, $password) < 1)
{
$this->form_validation->set_message('valid_password', 'The {field} field must have at least one number.');

return FALSE;
}

if (preg_match_all($regex_special, $password) < 1)
{
$this->form_validation->set_message('valid_password', 'The {field} field must have at least one special character.' . ' ' . htmlentities('!@#$%^&*()\-_=+{};:,<.>ยง~'));

return FALSE;
}

if (strlen($password) < 5)
{
$this->form_validation->set_message('valid_password', 'The {field} field must be at least 5 characters in length.');

return FALSE;
}

if (strlen($password) > 32)
{
$this->form_validation->set_message('valid_password', 'The {field} field cannot exceed 32 characters in length.');

return FALSE;
}

return TRUE;
}
//strong password end
// ################################# End Password Reset #################






// #############################################################

public function changePassword($id='')
{
$data['title'] = 'Change Password';
$this->form_validation->set_rules('old_password', 'old password', 'trim|required|callback_password_check');
$this->form_validation->set_rules('new_password', 'new password', 'trim|required');
$this->form_validation->set_rules('confirm_password', 'confirm password', 'required|matches[new_password]');
$this->form_validation->set_error_delimiters('<div class="error">', '</div>');
if($this->form_validation->run() == false) {
$this->load->view('admin/header');
$this->load->view('admin/profile');
$this->load->view('admin/footer');
}
else {
$data['oldpass'] = md5($this->input->post('old_password'));
$newpassword = md5($this->input->post('new_password'));
$data_array = array(
'id' => $id,
'password' => $newpassword
);
$updatedata = $this->Admin_model->password_reset($data_array);
$this->session->set_flashdata('successmsg', '<div class="alert alert-success" text-center"><h3>Your Password Successfully Updated !</h3></div>');
redirect('admin/profile');
}

}

public function password_check($old_password)
{
$id = $this->session->userdata('adminid');
$user = $this->Admin_model->password_verify($id);
if($user->password !== md5($old_password)) {
$this->form_validation->set_message('password_check', 'The {field} does not match');
return false;
}
return true;
}

// #############################################################




}

public function reset_password_verify($id,$data)
{
$this->db->select('*');
$this->db->from('admin_info');
$this->db->where('id',$id);
$this->db->where('password',$data['oldpass']);
$qry = $this->db->get();
return $qry->result();

}
public function password_reset($data_array)
{


$this->db->where('id', $data_array['id']);
$this->db->update('admin_info', $data_array);
return true;
}


public function password_verify($id)
{
$this->db->where('id', $id);
$query = $this->db->get('admin_info');
return $query->row();
}