Have you tried http://yourserver.com/admin/replace.php ?
Yes. Already but still not working. Maybe i did it wrongly. Please advise me.
Do i need a full path for example, enter 
and replace with 
or just enter http://oldserver.com replace with http://newserver.com ?
Thank you
Have you read http://docs.moodle.org/22/en/Moodle_migration by any chance?
Once after a migration, I experienced that by editing and saving one of the activities in a course, the links to images were automagically updated.
Just did the same. Bizarre - links are all magically fixed. Any thoughts on a similar magical fix for the distorted pdfs and ppts?