1. Check under which users is running your http server
[root@rippervp pro-soccer]# ps aux | grep -i http
apache 1898 0.3 5.5 306092 43732 ? S 10:13 0:04 /usr/sbin/httpd
Im my case httpd is running under username apache
2. Change ownership of your wordpress directory
chown -R apache:apache public_html/
I’m using centos 5