Few day ago i was received an email form my webserver (hostgator) saying that "Malicious files detected on website" and then they change the permission of access of the file and my website was show message that you have no permission to access this page.

What is SiteLock-PHP-BACKDOOR-GENERIC-awq.UNOFFICIAL?

SiteLock-PHP-BACKDOOR-GENERIC-awq.UNOFFICIAL is arise when there is something error or unpredictable function activities in your code that make your software unprotected. Means there are pieces of code that allow attackers to bypass authentication, maintain their access to the server and can affect the websites data. These error code may be as simple as a single line of code, allowing the execution of remote code, or complex algorithms, providing different functions to the attacker.

How i resolved my error? (THE SOLUTION)

i go through my codes but i did not find any error as per my coding knowldge.  Next i delete half of the code and then scan it with server anti-virus (i find it in my server's cpanel > advance > virus scanner).

If your anti-virus still detect virus it means, defected code is in the un-deleted code. Put deleted code back to your code and check half of the code where defect is detected and again scan the file or directory. Do this untill you get the exact line which causing this this problem. Remove this code or write it using different method and recheck it. Screenshot of my defected code is shown in above image. This steps will resolve your proble.