Instructions
Open your spellbook once you log in to your hunter. Click "Beast Mastery" on the right side and then click and drag the "Call Pet" and "Revive" spells to your action bars.
Click "Call Pet" and click your pet's icon from the boxes that appear. If that does not summon your pet, click "Revive Pet." If your character does not begin to assume a casting stance and revive your pet, visit the nearest major city.
Go to the stable master once in the city. If you are unsure of the stable master's location, right-click a guard and click "Stable Master." The guard will pinpoint the location on your mini-map.
Right-click the stable master and look at the "Active" pets and the stored pets. If your pet is in storage, click and drag its icon to an "Active" box. If your pet is in an "Active" box, drag it to a storage box and then back to an "Active" box. Attempt to summon your pet by clicking "Call Pet." If you still cannot retrieve your pet, click the red question mark on the Micro Menu and submit a Help Ticket to a Blizzard Game Master.