Items delivered but not in inventory

[Setsumi]

I bought something's off of Marketplace and it says they were delivered but I don't see them in my inventory. They aren't in the recent folder, trash, or objects. 

[Peewee Musytari]

If they are marked as delivered the seller got paid, so send an IM to them to ask for a replacement.

That is usually the fastest way, but in the unlikely event that that doesn't work you can submit a ticket on https://support.secondlife.com/create-case/ for redelivery.