Melted plastic on a stove does not necessarily ruin the surface. It's often possible to remove the melted plastic from the surface of a stove.
Melted plastic on a stove top can most likely be removed by using a dull knife or spoon, a lubricant such as WD-40, acetone nail polish remover and razor blades. In addition, a soft cloth, water and mild soap may be useful.
To remove the melted plastic, first let the surface of the stove cool completely. Once cooled, peel as much of the plastic as possible. Next, gently scrape the plastic using the dull knife or spoon, taking care not to scratch the surface of the stove. If plastic remains, spray it with lubricant, let it set for a few minutes, and gently scrape it offwith a razor blade. Use acetone nail polish remover to remove any remaining plastic or gently clean it with a scrubber, using a circular motion. When the plastic has been removed, clean the surface of the stove with mild soap and a soft cloth to remove traces of the acetone nail polish remover or lubricant.