Let's just say that you're in a situation where you can't track down a certain individual you want to seek and ask Forgiveness from, and you want to do Teshuvah to the Person wronged with Love and Remorse. However, you have no way to track them down and talk to them in the first place. Let's just say you insulted the person. Is doing the Teshuvah of never insulting people again being extra careful towards others' feelings, complimenting them, making them feel loved and accepted, and being Favorable in the Eyes of other people a starting point? Some sins are so severe that one has no share in the world to come, like embarrassing someone in public, how can i repent for embarrassing someone in public if i don't know the person and have no way of finding them therefore asking for forgiveness? What should i do?

Shalom, What you suggested is a great idea. Let's focus on the future. From now on let us try to speak only good about people, and avoid speaking 'lashon hara'. Additionally, it might be a good idea to learn the book 'Chafetz Chaim' and 'Shemirat Halshon' a little a day. All the best! Sources- See here: https://www.yeshiva.org.il/ask/135294