How to Troubleshoot "The procedure entry point OCIClientVersion could not be located in the dynamic link library OCI.dll"

Once upon a time, i have been installing xampp that will be connected to oracle database (php connect to oracle) in windows. After installing i have commented the line to enable php_oci8.dll and php_pdo_oci8.dll.
But when i try to start apache, there is error as below :

How to solve this ??
There are somethings that you must check :

1. Stop apache
2. Check that you have set ORACLE_HOME environment variable
3. Remove or rename file oci.dll under c:/xampp/apache/bin/ and under c:/xampp/php/
4. Start apache