This is usually down to a water related issue, so take a closer look at the condition of the soil around your plant. If the leaves look and feel thin, chances are the soil will be bone dry and the roots stressed from searching for water. Soak the potted plant in a bowl of water for around 15 minutes. This will give the plant a chance to rehydrate. Allow to drain thoroughly before popping back in position.
If your rubber plant’s foliage is droopy and turning yellow (or brown) , overwatering is the most likely problem. Carefully remove the plant from its pot, tease away the sodden compost and repot using fresh. Refrain from watering until the soil feels dry to the touch.