Go to Tools>Options>Password for the Master Password if you are like me and couldn't remember what your Master Password was the following will help:
Customer Service can do a Master Password Reset which allows you to open any client file. The Account Owner would need to contact Customer Service at 800-434-6818.
It's easy to remember a password if you use something that is easy to remember. I believe a survey was taken recently and the number one password used was - IntuitSucks#666