There are two ways to access inventory and they have very different purposes. A typical employee that needs to access the inventory for searching outside of a work order, creating purchase orders, transfers, to edit an item or add an item would likely access the inventory through Utilities. An employee that needs the ability to do all of the previously listed functions as well as delete items, create or manipulate multiple items at once, would need to access inventory from Setup.
Setup: To access Inventory via setup, click the Setup button on the ribbon, type in "inv" in the search box, and then click Inventory Setup > Inventory Materials in the left-hand menu.
Utilities: To access Inventory from the utilities menu, click the Utilities button on the home ribbon and then click on Inventory.