Magento Error fix

I have mydomain.com website built in wordpress.

I created a mydomain.com/retail folder and i installed a magento website here.. Once i finish with the magento website and upload all products now i want to move it to:

mydomain.com/retail to mydomain.com

I have tried to transfer the folders and i received

403 Forbidden
You don’t have permission to access /retail/ on this server
Apacce2 Server at mydomain Port80

I’ve changed the index.php permission to 777 then i receive below error.

A file permissions error has occurred. Please check the permissions on the script and the directory it is in and try again.

Now it got a bit mess. I need someone to fix it. Can someone help?