If you are unsure where to go after all this, you may wish to hire a server administrator. As while, we'll try to help point you where we can, hosting is really outside our scope of support.
Checking and ensuring your permissions for your directories and files would be advised here. If you are running suPHP, suexec, or possibly other configurations, 777 will actually break and cause permissions errors. 755 in these cases would be correct for directories and 644 for files.
While permission errors to the database usually result in a different error, it is worth ensuring that the database user has full access.
This would be in our software's installation root, the same directory as conf_global.php. If you do not have one, then no need to worry about it.