Unable to access login page or my website I have been unable to access my website or log into my CMS. I have checked with the server and everything is OK there but all I am getting is a blank page.

I updated craft manually following the instructions given.

I also have a staging site which I use for sharing with my client and this all works fine.

Is there anything I need to be checking? What will have stopped the website from working? I would really appreciate any help you can give with this.

Thanks in advance.
One small detail that can cause the front-end and back-end of your site to result in a blank white page, is if you have a syntax error in your general.php file, such as a missing comma at the end of a line.  If you've just made a recent edit to your config files, take a closer look at them and make sure that you don't have any small errors.

For example, the following multi-environment config is missing a comma at the end of the omitScriptNameInUrls setting, and that minor detail would make both the front-end and back-end of a site result in a blank white page: 

return array(
    '*' =&gt; array(
        'omitScriptNameInUrls' =&gt; true
        'devMode' =&gt; false
    )
);