What are the steps should I follow if my custom module gets a 404 not found error?

Question

I have created a custom module which will save some data in the database and will show in the front end.
But when I see in the front end it gets me a 404 not found error.
I think the error is in the config xml file .
could anyone suggest what are the steps to follow if I get this type of issue ?
This is my config file..

<?xml version="1.0" encoding="UTF-8"?>
<config>
<modules>
    <Magentostudy_News>
        <version>1.0.0.0.1</version>
    </Magentostudy_News>
</modules>
<global>
    <models>
        <magentostudy_news>
            <class>Magentostudy_News_Model</class>
            <resourceModel>news_resource</resourceModel>
        </magentostudy_news>
        <news_resource>
            <class>Magentostudy_News_Model_Resource</class>
            <entities>
                <news>
                    <table>magentostudy_news</table>
                </news>
            </entities>
        </news_resource>
    </models>
    <helpers>
        <magentostudy_news>
            <class>Magentostudy_News_Helper</class>
        </magentostudy_news>
    </helpers>
    <blocks>
        <magentostudy_news>
            <class>Magentostudy_News_Block</class>
        </magentostudy_news>
    </blocks>
    <resources>
        <magentostudy_news_setup>
            <setup>
                <module>Magentostudy_News</module>
                <class>Mage_Core_Model_Resource_Setup</class>
            </setup>
        </magentostudy_news_setup>
    </resources>
    <events>
        <before_news_item_diplay>
            <observers>
                <magentostudy_news>
                    <class>Magentostudy_News/observer</class>
                    <method>beforeNewsDisplayed</method>
                </magentostudy_news>
            </observers>
        </before_news_item_diplay>
    </events>
</global>
<frontend>
    <routers>
        <magentostudy_news>
            <use>standard</use>
            <args>
                <modules>Magentostudy_News</modules>
                <frontName>news</frontName>
            </args>
        </magentostudy_news>
    </routers>
    <layout>
        <updates>
            <magentostudy_news>
                <file>magentostudy_news.xml</file>
            </magentostudy_news>
        </updates>
    </layout>
</frontend>
<Admin>
    <routers>
        <adminhtml>
            <args>
                <modules>
                    <Magentostudy_News before="Mage_adminhtml">Magentostudy_News_adminhtml</Magentostudy_News>
                </modules>
            </args>
        </adminhtml>
    </routers>
</Admin>
<adminhtml>
    <layout>
        <updates>
            <magentostudy_news>
                <file>magentostudy_news.xml</file>
            </magentostudy_news>
        </updates>
    </layout>
</adminhtml>
<default>
    <news>
        <view>
            <enabled>1</enabled>
            <items_per_page>20</items_per_page>
            <days_difference>3</days_difference>
        </view>
    </news>
</default>

Thank you.

Answer 1

You can debug why your module controller is not used here

app/code/core/Mage/Core/Controller/Varien/Router/Standard.php in the method match()

this is where magento tries to find the controller/action for current request. I suggest you use xdebug to debug this

inside this foreach loop

$found = false;
foreach ($modules as $realModule) {

you will see this line

$controllerClassName = $this->_validateControllerClassName($realModule, $controller);

This is where magento tries searches for your controller. In the method _validateControllerClassName() it will generate a class name and file path that it expects from your controller.

Answer 2

I found what was wrong in the config.xml.
The <modules> tag under <router> should be <module>.
So the code should be like..

<routers>
    <magentostudy_news>
        <use>standard</use>
        <args>
            <module>Magentostudy_News</module>
            <frontName>news</frontName>
        </args>
    </magentostudy_news>
</routers>