Instructions
Check online retailers. Large lava lamp distributors sell parts like a base or new light bulbs in addition to lava lamps. Be sure to match the base to the metal top of your lava lamp.
Find the original distributor of your lava lamp and call them to ask for replacement parts. If you can't remember the name of the company, check on the lava lamp globe or on the base. These are the most common places for distribution stickers. The sticker will have a product number and the company name. If needed, look up the company name online to find its phone number. They will ask for your product number to know the right part to send you.
Buy a used base from an auction site. Measure the size of your lava lamp globe for the right sized base. Search on used or auction sites for a replacement base. Ask if a bulb is included; if not you will have to find a replacement bulb as well.