Can you tell me if it's ever possible to get over ptsd without any therapy?

In general, no: PTSD is one of the most severe types of anxiety disorders. CBT (COGNITIVE BEHAVIORAL THERAPY) is a type of therapy that is structured , highly recognized and has established evidence to help. A variant known as Trauma Focused CBT is particularly helpful. Mediation , routine sports/exercise and other grounding lifestyle changes are indispensable. By the way, I do transcendental meditation :)

Easier: Yes, it is possible for PTSD symptoms to decrease over time without therapy. That being said therapy and medication is the best combination of approaches to deal with PTSD in a much shorter period of time. Why prolong suffering?

Healing over time: Many people who develop PTSD do get better over time on their own, but about 1 out of 3 people who develop PTSD will continue to experience difficulties that interfere with their lives and daily functioning. If you have symptoms, therapy and/or medication can help you cope.