The facts are very limited in your question. I assume you purchased a lot in a subdivision that either was not properly subdivided pursuant to the local jurisidction's subdivision or zoning ordinances or there is somehow a defect in the final plat that was recorded in the land records. Does your subdivision have a homeowners association? If so, you may want to enlist their help in clearing up the problem. Do you have title insurance? If so, you may want to file a claim since you state that there is now a purported cloud on you property's title. The title company may presssure the developer to address the subdivision problem.