While in cruise flight the pilot realized he had lost elevator control. The pilot attempted to determine if there was any way to re-establish elevator control but was unsuccessful. He was able to maintain pitch control by increasing or decreasing engine power. During a precautionary landing the airplane was damaged when it impacted the runway hard and damaged the firewall. On scene inspection of the aircraft’s elevator control system by an FAA Airworthiness Inspector revealed the bolt that connects the aft elevator push pull control tube to the pilot and copilot's control stick bellcrank was missing, and was not found during a thorough inspection of the area. In addition, the bolt that connects the forward push pull tube to the control stick bellcrank was ready to fall out. These bolts are an AN type drilled shank bolt requiring a castellated nut and cotter pin for security. Neither of the nuts or cotter pins were found. The aircraft has 197 hours total time. The last condition inspection was performed 2 months and 24 operating hours prior to the accident. It could not be determined if the cotter pin had ever been installed.