Most gift plants from florists are not designed to survive much beyond the holiday they were bought for.  They have been grown and forced to bloom at a set time, often at the expense of a decent root system.  As a consequence, they quickly fade out.

Italian Heather, Erica ventricosa, is extremely needy in its requirements.  I found a page of care instructions here:  http://coastalnursery.com/italian-heather-care-instructions/ .  However, in my copy of The House Plant Expert by D.G. Hessayon, the author adds:  "...these plants will give disappointing results in a  centrally heated room.  In hot, dry air the leaves drop very rapidly, so only an Erica for display in winter if you can proivde a cool and well-lit spot.  Pay careful attention to watering - never use hard water and make sure that the compost is never allowed to dry out...Even under cool conditions and with the compost kept suitably moist you cannot expect an Erica to survive for long in the home."

My advice would be to dispose of the plant, unless you are willing to devote an unreasonable amount of attention to this short-lived plant.