安装php5.2.6后,php信息将无法显示

For some reason I need to downgrade the php5.4 to 5.2.6 I've already manually installed the php5.2.6 after compiling it was success.. no errors where encountered. but funny thing is that when i php -v it is telling me that php is not installed.

Sever setup default apache httpd is installed. removed php5.4 and downgraded it to php5.2.6

I've already tried everything I found over the net but still can't figure out what I have missed along the way.. I'm just a newbie here and your expert advice will really help.. Thanks in advance..

Cheers