To reset the password for a Mojang account (you log in with your email address) visit https://my.minecraft.net/en-us/password/forgot/
To reset the password for an older Minecraft account (you log in with your username), you will need to go to account.mojang.com/migrate and follow these steps:
1. Go to account.mojang.com/migrate
2. Press the "Forgot your password?" link
3. Enter your account email and username, and press "Request password reset"
"InvalidCredentialsException", if you receive this error please read this help article.
If you have attempted to reset your password and are not receiving the reset email, please visit our article on not receiving system emails. Keep in mind that it is possible to have multiple accounts or account types. Minecraft accounts are explained here.
If you are unable to reset your password, please locate your transaction ID, then contact customer support.