Firstly, make sure you know which email you used to create your Packback account. When in doubt, it's usually your school email!
After that, go to https://questions.packback.co/password/forgot and enter your email to request a password reset link. Follow the instructions to use the link and reset your password!
Note: Once you're prompted to this page (see photo below), be sure to not request for another password reset link immediately because it will invalidate the original link!
If the above practice doesn't work and you are still experiencing issues with your password, there may potentially be something else going on with the password reset link. Check out this article for more information!