PHP: Forget Password Module working unexpectedly - php

Question

I am making a simple forget password module.
User will enter his username, security question answer, and new password.
So if the user is found in the database table, the password will get updated
or else it will show an error.
FORM CODE :
<form id="fogform" method="POST">
<div class="form-group row">
<label for="un" class="col-form-label col-md-6">Username:
</label>
<div class="col-md-6">
<input type="text" class="form-control" name="un" placeholder="Enter your username" required>
</div>
</div>
<div class="form-group">
<div class="row">
<label class="col-form-label col-md-6" for="ques">Security
Question:</label>
<div class="col-md-6">
<select name="ques" class="form-control" required>
<option value="" selected>Choose any:</option>
<option value="In which city you were
born?">In which city you were born?
</option>
<option value="What was your first
pet's name?">What was your first pet's name?</option>
</select>
</div>
</div>
</div>
<div class="form-group row">
<label for="answ" class="col-form-label col-md-6">Your Answer:
</label>
<div class="col-md-6">
<input type="text" class="form-control" name="answ" placeholder="Enter your answer" required>
</div>
</div>
<div class="form-group row">
<label for="npwd" class="col-form-label col-md-6">New Password:
</label>
<div class="col-md-6">
<input type="password" class="form-control" name="npass" placeholder="Enter a New Password" required>
</div>
</div>
<div class="form-group row">
<label for="rpwd" class="col-form-label col-md-6">Retype Password:
</label>
<div class="col-md-6">
<input type="password" class="form-control" name="pass" placeholder="Retype the password" required>
</div>
</div>
<div class="form-group row">
<div class="col-md-5 offset-2">
<button type="reset" class="btn btn-danger">Reset</button>
</div>
<div class="col-md-5">
<button type="submit" name="fogo" class="btn btn-success" data-toggle="modal" data-target="#infomod" form="fogform">Submit</button>
</div>
</div>
</form>
PHP CODE:
<?php
session_start();
$cn=mysqli_connect("localhost", "root", "", "imedtalks");
if(isset($_POST['fogo']))
{
$fogsql = "SELECT uname, passwd, que, ans FROM register WHERE passwd='".$_POST['pass']."'
AND que='".$_POST['ques']."' AND ans='".$_POST['ques']."' AND uname='".$_POST['un']."' ";
$rslt=mysqli_query($cn, $fogsql);
if($_POST['npass'] === $_POST['pass'])
{
if($row=mysqli_fetch_assoc($rslt))
{
$fogsql2 = "UPDATE register SET passwd='".$_POST['pass']."' WHERE que='".$_POST['ques']."' AND ans='".$_POST['ques']."'
AND uname='".$_POST['un']."' ";
if($cn->query($fogsql2) === TRUE)
{
echo " <script type='text/javascript'>alert('Password Reset Successful!')</script> ";
echo " <script type='text/javascript'>window.location.replace('http://localhost/PROII/HomePage.php')</script> ";
}
}
else
{
echo " <script type='text/javascript'>alert('Password Reset Unsuccessful! Try Again.')</script> ";
echo " <script type='text/javascript'>window.location.replace('http://localhost/PROII/HomePage.php')</script> ";
}
}
else
{
echo " <script type='text/javascript'>alert('Password Verification Failed! Try Again')</script> ";
echo " <script type='text/javascript'>window.location.replace('http://localhost/PROII/HomePage.php')</script> ";
}
}
?>
So here, whenever i try the wrong way it gives unsuccessful message but even for right field data, it gives an error.
I am new to php, that's why i can't understand where its going wrong.