I had minor testicle pain for 1 day but now it's completed stopped? also i'm not sure if it was the testicle or the groin.

Many possibilities : Including testicle itself hernia muscle or even urine infection. Best to get checked out even if symptoms gone to make sure nothing that can cause recurring issues

You need to see a dr: Testicular pain can be due to many causes. Inflammation, infection or hernia can cause such pain as well as more sinister causes such as Testicular cancer. It is best to see your doctor who can carry out a thorough examination as well as arrange imaging such as Ultrasound to determine the cause of the pain

All gone = good: If the pain was only transient and not associated with any other symptoms then I would not worry too much and continue to watch + wait. If however you think you've had other symptoms (pain with urination/pus from the penis, swelling or redness) or you've had unprotected sex then you should probably see a Dr or a sexual health clinic.