First you should find a “Redelivery Terminal” located at the main store, this one works for hairs and body shapes purchased at the mainstore and should work for marketplace purchase as well.
You will find this terminals most likely near every product range area (such as hairs or body shapes). Simply touch this terminal and follow given instructions.
If this fails, please send a notecard with transaction details (if purchased from SL Marketplace, provide your name and Order ID), so that the product box could be send as soon as possible to you.
Transaction details can be found at your SL account website: https://secondlife.com/my/account/transactions.php
Transaction details for marketplace orders can be found here: https://marketplace.secondlife.com/orders
Most products at the Main Store are sold out of “buyable” prims.
You do NOT have to accept any delivery.
The item you have purchased will be right after create a folder inside your inventory. If you are not able to locate it, try using the search option of the inventory, enter the name or a part of the product name to find it. If this failes, try relog to SL (makes sure your viewer cache is always healthy also).
If all fails… contact me by notecard as described above.