why I cant get a list item that exists?

Question

Is there a difference between checking a pages library and a list in terms of powershell commands?

The following cmdlet is not returning me an item, and when I checked the browser I see the list item with that id

Its a pages library

It says item does not exist or it may have been deleted by another user.

$spSite = Get-SPSite "https://mysite.com"
$spWeb = $spSite.OpenWeb("https://mysite.com/myweb/practical-tips")
$affected = $spWeb.GetList("/Pages")
$manager=$site.workflowmanager
$culture=[system.globalization.cultureinfo]::currentculture
$association=$affected.workflowassociations.getassociationbyname($wfname,$culture)
$data=$association.associationdata
$wfname="News approval workflow"
$wfrunoption=[microsoft.sharepoint.workflow.spworkflowrunoptions]::synchronous

$item = $affected.GetItemById(80)

Answer 1

SpWeb.GetList wants "The server-relative URL to the root folder of a list", like in your case:

$spWeb.GetList("/myweb/practical-tips/Pages")

http://msdn.microsoft.com/en-us/library/microsoft.sharepoint.spweb.getlist.aspx