Thank you for adding a post. I'd be delighted to help ensure your co-worker will be able to log in and open QuickBooks succesfully.
First, please make sure your co-worker opens the same file. If the correct file was open, and still can't log in, you can have the company admin reset the password.
If you’re not an admin user, your QuickBooks admin can reset the password for your co-worker. Contact your admin and have them follow the steps in this article for resetting a user password: Reset Password.