If you click on a web link in a ticket notification email and your web browser displays a page doesn't exist, or access denied error page, this will almost certainly be because you have two accounts in the help desk and the ticket you tried to access is under one account but you are logged in to the other one.
The remedy is for us to merge your help desk accounts, which you can ask us to do by submitting a request in the General category. Please copy and paste the email which contained the problem web link into your request (so that we can confirm that having multiple accounts is the cause, and as evidence that you have access to the ticket via the other account).