1. Login at the Customer Control Panel with your main account's username and password.
2. Once logged in you'll see a link that says "Login via IP Address" under the Parallels Plesk Panel section at the bottom left hand side of the page.
3. Once you click on that link, a new window will come up, you might get a certificate warning, just click continue, then your Plesk Panel will come up.
4. Now if you've changed your password to Plesk from what it was originally set to when you started out, you will need to contact InfoQuest Support and ask them to reset the password back to the original password again. They will reset it back to the original password that is set in the customer control panel, which you can view under the "VPS Managment" tab.
Once it has been reset, you can login from the InfoQuest Control Panel again.
If you change the password again, you will not be able to login through InfoQuest's Control panel.