The procedure entry point OCIStmlRelease could not be located PHP 5.6 OCI8 xammp

I am using php 5.6(Xammp Apache Server) with oracle 11g installed.My php to oracle connectivity was working fine until yesterday i suddenly got this error when i start Apache service from the Xammp Control Panel.I got this error message.

httpd.exe - Entry Point Not Found

>the procedure entry point OCIStmlRelease could not be located in the dynamic link library E:\xammp\php\ext\php_oci8.dll

Here are the configurations which i have done I have uncommitted the line in php.ini

extension=php_oci8.dll

I have added following files in the php\ext folder

php_oci8.dll and php_oci8_11g.dll

I have installed the Oracle Instant Client 11g and added it's path in Environment Variables to

C:\Oracle\instantclient_11_2;

but still i am getting the above error when i start my Apache server from xammp control panel and if i connect to oci8 using php then i get this error.

Fatal error: Call to undefined function oci_connect()

i have been searching for almost 3 days on this issue but still could not find anything.It will be really helpful if someone can help me out on this.