Only you can forgive yourself. Nobody else can forgive you. Others can only acknowledge if you tell them that you have forgiven yourself. This acknowledgement that comes from others is what we call they have forgiven us. But, it's you and only YOU who can forgive yourself.
See, forgiveness has been made needlessly complicated between human beings. You want to seek forgiveness because you're so miserable. Reason for your misery is you do not know what it is to forgive yourself. The most important person that you have to forgive is yourself. Do that and do yourself and everyone a favor.
People lead miserable lives because they do not know that it's only they who can forgive themselves and nobody else. They are sad because the person from whom they seek forgiveness is not there anymore. Or the person may not reachable. Or there may be some other reason.
Why worry about all this? Your conscience is pricking you. Right? It's time to make peace with yourself.
Just list down the wrongs you committed. Sincerely and seriously ponder over them and forgive yourself completely. It's possible. Just do it as part of your prayers or temple visit or something else.
Once you have forgiven yourself, if it matters and if it is possible, let the other person know about the same. You can also ask for forgiveness from others but in reality what you are asking is mere acknowledgement of what you have already done. Sometimes it helps and sometimes it does not.
When God has given every conceivable power to humans, do you think God has not given us the power to forgive ourselves? We just do not know it. First forgive yourself for anything and everything. You are way too precious to wait for someone else to do it for you because only you can forgive yourself.
Asking others for forgiveness is like asking them take a shower or even funnier asking them to give you one because you feel you need one. How crazy is that? What is needed is you take a shower of forgiveness to cleanse your soul.
All these complications arise because we are way too immature. We are on our way but got a long way to go before we can laugh at the absurdity of all this. Same river of consciousness flows through all of us. And here one drop of water in the same whirlpool of life is asking the other drop to do something. You can not even say there are drops of water. Water in the river is so seamless and one.
But, till we see the unity and remove all the separateness, we will need all these rudimentary techniques so that we do not go crazy about this simple but most powerful soul cleansing technique - forgiveness.
If you think that you can forgive someone else or someone else has to forgive you, fine. You will move to next level of awareness when you are ready. But, let that not stop you from forgiving yourself. Continue to forgive others but first forgive yourself because as they say - put the oxygen mask on yourself first before trying to put it on your dependents. Without forgiving yourself, you will wither away because unclean conscience is highly toxic.
Just do not say - I forgive myself for not forgiving myself.