A complaint and summons (i.e. lawsuit) must go to the "Registered Agent" of the corporation, or to an officer, director, or managing agent of the corporation. If it is not a corporation, then list the owners of the business as the defendants. If there is no record of the corporation's registered agent or principal place of business, sue the corporation in any county where it does business.
If there is no record of that business as a corporation, then go to the Register of Deeds Office in the county where the business has an office. The Register of Deeds, which is in the courthouse, has the names of owners of businesses in its county. Write the business owner's name on the court papers as the defendant. If the Register of Deeds Office does not have information about the owners or their addresses or about any registered agent, sue the business in any county where it does business.
A process server may try to serve the business through the Secretary of State. If this continues to be unsuccessful, the court case can proceed without their knowledge. Often leading to a default judgment.