What to use instead of permalink_single()

Hi,
I see that — php permalink_single(‘file’) — doesn’t work any more. What can I use to make content show in just the templates I want? e.g. I would like visitors who click an item title in “sales.php” to see that item in the “sales.php” template. See what I mean here: https://www.oakleyhorses.com/beta/sales.php
Can anyone help?
Many thanks,
Eoin