Please move this to Products where it belongs. The specified item was not found. is for generic, non Marketo related questions.
What you request is a standard Marketo behavior. If the person is known in your DB and clicks on a link in a Marketo email then land on a MARKETO landing page, the fomr will automatically be prefilled, unless you have explicitely deactivated prefill in your instance or in the form.
if the landing page is not a Marketo LP, then prefill will not be available as this only work on Marketo LP's.