Magento-Home Page-Store or Store View is not showing up-404 error: Page not found

Checklist :

1. Make sure the default store view of your defaut store of your default website is not disabled.
2. Flush your cache's
3. Reindex Data
4. Set Main website as default and and then set back your website as default.

The last option worked me with once I changed the Default store for my default website and did every thing till 7th point untill I hit and tried 8th one and it worked for me.

If this is not helping you need to debug the issue since it may either be your .htaccess issue or issue from index.php
Open the index.php in root directory of the Magento installation and comment the line
Mage::run($mageRunCode, $mageRunType);
 (you will find this line near the end)
 Run your website if you still find a 404 page not found error its an .htaccess issue try renaming the same

Else try this hardcode in index.php

Just above the code mentioned above type in the following code

/* Store or website code */
$mageRunCode = 'code of store view to load';

/* you will find the code field when you edit your store view type the same code exactly here */

/* Run store or run website */
$mageRunType ='store';

(make sure you type this just before the code line "Mage::run($mageRunCode, $mageRunType);" ) inorder to override default value of these variables

If you are able to open your store view here you need to go back and check store Management.

Post here if you further have any issues