I installed WAMP server 2.4 the latest one on its website which currently support PHP 5.4 and Apache 2.4. This works successfully. When I tried to downgrade the PHP version to 5.2 or another lower version, the system rejected this downgrading saying my Apache version is not compatible. So, I tried downgrading my Apache version, but it said it couldn't because my PHP version isn't compatible... apparently I am looping without being able to downgrade the PHP. Is there any solution for this?. I would very much appreciate any help on this.

there is one solution for that
1. unistall the updated version
2. find the suitable php version or apache and then install it

hope this helps

Thanks for your insight. I nstalled the new version of WAMP in order to utilize PHP 5.4 for a Drupal 7 website, but I needed lower version now in order to operate another site that works only on the downgraded version of PHP. If I uninstall the WAMP 2.4 as you suggested, the Drupal 7 website will not work. What do you think?

did you try xampp?
well i think its better to use because of its multiplatform compatibility

Unforetunately I am very used to WAMP, but thanks for the hint. Where is the web root folder in the case of XAMP. I had installed but only used it on simple php programs.

Thanks for the hint and I started to use XAMPP as well installing back versions (XAMPP 1.6.8) to get PHP 5.2 variants installed. Thanks.