Buy a new ballast suitable for the wattage of your lamp, ballasts sold today are electronic, and they can range from $12-$200, depending on your light. Use the old ballast to determine the exact wattage of your new one. Ballasts can be found at most major hardware stores. When buying, you'll need to know:
Your light's wattage
The number of bulbs in the light
The wiring system on your old ballast.[4]