How do I stop thinking about a friendship that has ended?

If you want it to be saved, try to communicate. Say it to your buddy that you value the friendship greatly, and if unintentionally something from you has hurt him/her, then he/she can forgive you, and that you promise to be more sensitive to your friend's feelings for the future. And in case your friend has hurt you, you need to tell you friend that he/she has and take your time before you two can be talking again. But if your friend is rude and says 'Go away from my life', then should go away but with telling him/her that you would be patient and try to contact with your friend again somewhere down the line when the rudeness would have melted.

i focus on other things..true this friendship was the best and i enjoyed it very much but sometimes tings aren't meant to last and we get hurt or we hurt them sometimes its best to leave rather than get hurt even more and even if they dont want to keep going you know you tried your best and you did everything for that person but move on because there's more friends you can find

Start another one. Life is too short to hold on to things that no longer serve you (or the other person). Make some friends in your local community, or here on the platform, and soon your relationship ending will be a thing of the past. Just think about a 'tragic' thing like a bad test grade in the past that really messed you up. Looking back on it now, now much of a problem was it in the grand scheme of things? That will be the status of this issue in a few months after you have moved on. Be strong!

It's hard to bear losing a friend after all avenues to salvage a friendship have been exhausted. He/she can never really be replaced but you can still try and find somebody to help you fill the gap. The characteristics that a good friend must have , are after all still universal. Find someone who will be able to make you laugh , stick by you through thick and thin, support you and always tell you the truth. Grieve the loss of your former friend and then move on. Let somebody help you pick up the pieces.

Maybe try to make more friends or take up a hobby so that you can enjoy yourself and not have to think about a friendship that has ended.

in December 2017 I had my pastor and his family sever ties with me. It was a complete abandonment as they did not discuss anything with me nor try to give me reasons; the best I got was the pastors (college age) son telling me I'm barely tolerable. Then I was punished and all but excommunicated (I was allowed to main service only--though I never went back). That would ultimately lead me to mental health and to this website. I never really got answers, closure, or understanding; but the only thing you can do is try to move on. Harder with Covid going on, but you can invest in some hobbies. Meeting new people can help but if you're like me you'll also be battling trust issues if this was done by a person of trust. Realistically we never forget our old relationships; they just gradually have less impact on us.

Look at future prospects and keep yourself busy with tasks that work towards that future. Forward...

In life we often face with overthinking about loads of things. And sometimes seems as there is no way to stop doing that. But thinking about thing we can resolve is not helpful. We should start doing and not just thinking. So there is just one way, to speak with your ex friend and find out are you really missing their frendship, or you are just remembering a good moments. Or be sociable, and try to make some new friendships. People are sociable beings.