Question: Because of some reason my site stopped working. After that I have uploaded the backup which I had created earlier.

I am getting a "404 Not Found Error The resource requested could not be found on this server!"
getting this on every page except `index.php` and also not able to login into the admin panel.

I already cleared the cache memory and set the `is_active` option to 1 in `core_website`, `core_store` and `core_storegroup` tables in phpMyAdmin still getting an error... I've tried so many links to solve this issue but the problem didn't resolved till yet.

Answer: 
the solution for 404 errors on magento 1.9 was to 1-reindex data and 2-flush cache storage
Thanks after spending hours looking for a permission or apache issue, the simple fact that copying magento files from a Nautilus window into apache www is not correct.

There is a "hidden" `.htaccess` file that you cannot see. So either do a manual copy of the `.htaccess` file or extract directly into the `www/html/magento`. You can verify the hidden file using a sudo edit just to check if it exists. This corrected all the 404 errors even though `index.php` was visible in the browser.