Partner changed the password to QuickBooks. Now we have no access.

Thanks for visiting QuickBooks Community, @BartHumphries.

Access permissions protect the company file from unauthorized access, so an Admin on your QuickBooks company file will need to make this change.
Here are the steps for QBDT (Windows):

1. From the Company menu, choose Set Up Users and Passwords.
2. Select Set Up Users.
3. Pick the user that needs to change their password in the User List section.
4. Click Edit User.
5. Enter the new password.
6. Hit the Next button until you reach the last page, then click Finish.

For reference, check out the reset a user password section at the bottom of this article: Reset your password for QuickBooks Desktop.

I hope this helps! Please let me know if I can assist with anything further, I'm only a comment away.