If you are unable to access your saved passwords due to a forgotten master password, please do these steps to reset it. (Note: All passwords saved will be erased)

Enter chrome://pippki/content/resetpassword.xul into the Location Bar (address bar), press the "Enter" key and click "Reset".

Your passwords are lost without the correct master password because that MP is used to encrypt the passwords. To set a Master Password you need to enter that MP twice to get it set, so maybe you can have your three years old kid to type that MP another time. (S)he might have pressed only one key in the vicinity of the tab key.

You should set a master password to prevent that from happening. See Use a Primary Password to protect stored logins and passwords