It's most likely spider mites. A severe infestation makes all of the leaves turn brown and the plant looks dead. They love warm and dry conditions. To get rid of a bad infestation, just wash the undersides of the leaves daily for 3 to 5 days. Even if all of the leaves fall off, this breaks the breeding cycle of the mites on the plant.
General practice is to wash the undersides of the leaves of even a healthy plant weekly to avoid infestation.
To double check, just place a white piece of paper under the leaves and tap the plant. If you see a lot of tiny black spots, it's spider mites.
Smiles,
Lyn
