Beechcraft Sierra 24 pilot reported the left main landing gear was broken with missing parts.

Narrative

I noticed damage to my airplane after landing. After a normal visual approach and landing in ZZZ; I parked on the ramp in front of the FBO and proceeded inside. Once my passengers arrived; I loaded up the baggage compartment and stepped onto the wing to adjust the front seat. The airplane tipped onto its tail. This was extremely unexpected as the airplane was loaded well within all W&B limits. After righting the airplane and assuring there was no damage to the tail; we took a step back to inspect the aircraft. I noticed the airplane was sitting slightly nose-high; so I had a closer look at the landing gear. I found the left main gear had broken; with the compression rod broken and the compression discs and associated hardware missing. Due to this; the tire assembly had rotated from approx. 90 degrees aft to approx. 45 degrees forward; causing the balance issue. I am unsure of when this occurred; as taxi; takeoff; gear retraction/extension; approach; landing; and taxi-in were all normal. My best guess would be that it happened during gear extension on approach into ZZZ. We were on a strict timetable with our travel plans; so I didn't have further time to complete a more detailed inspection; and it was only after the fact when comparing photos that I realized there was any missing hardware. Hopefully more clues as to what happened will be revealed in the coming weeks once a mechanic inspects the gear during repairs. I will direct the mechanic to also closely inspect the right main landing gear for signs this issue could happen again on the opposite side; and conduct any recommended preventive maintenance accordingly. Additionally; I will be extra vigilant with my pre-flight landing gear inspections once it is airworthy again; keeping an eye out for components that appear loose or fatigued.