Found a cut like sore on my inner thigh don't remeber cutting myself what could it be.

Need more info...: Syphilis, herpes, laceration, chafing...It's hard to tell you definitively without unintentionally making you more worried. You are better served by seeing a healthcare professional about this since seeing the sore and understanding the context of your life will yield an answer.

Chafing: Sometimes an item of clothing can chafe in one spot and cause a sore. Multiple medical conditions can lead to sores, but if this is the only one, a local effect/cause is likely. If ti fails to get better, or if other sores develop in other areas, please be sure to get his checked by your doctor.