If you are having problems logging in, before changing your password read this to solve the problem.
Make sure you are using the correct letter case for both the username and password, i.e. capital letters and lower case letters must be correct. And realize that when logging in from an iPhone, the device usually capitalizes the first letter, so watch that.
Make sure you are logging in to the correct page. If you bought a Playbook download or upgrade or a CD download upgrade, you must login to those download areas... NOT the Premium Members section, which is different.