Hi and Welcome. My Name is ***** ***** I look forward to assisting you today with your question.
If you are referring to the Apple ID password, then you can reset the password ***** Apple's website. On your computer, go to this website --> https://iforgot.apple.com/
Enter your Apple ID. Use the "Email Authentication" method to reset the Apple ID password. Apple will send the reset instructions to the recovery email you setup with your Apple ID. It would be your other email accounts like Gmail, Yahoo etc if any, you registered with Apple.
If that didn't work, then reset again and this time use the "Answer Security Questions" and answer the security questions there to reset your account. After resetting the account, you will be able to download using it.
Please let me know if that didn't work, so I will continue to help you.
Remember, if you have any difficulty on resetting the account, please don't rate me bad or poor. Instead please reply back to me and I will continue to help you.