Have you installed the
patch? If not, do so and reload a save from the end of act 2. If you don't have a save to reload, it is also possible to get them back by swapping
Inventory files.
Unfortunately, the teleporter pyramids are not 'temporarily' taken in act 4, they are just taken. You don't really need them for act 4, though. They are useful in the BF, but the loss is mitigated by the changes to the overweight penalty in the latest patch (the summoning dolls can carry much more loot).