Feeling of guilty will not help you and it will not change anything। It may be what you have done in the past is giving you immense trouble and you always feel guilty of it।
With guilty feeling you are creating negative energy.
What to do ? Just let go the guilty feeling. Do not cling to it. Do not think over and over again the past incident.
Past is gone and it will never come back. There is little you can do or nothing at all you can do about it.
Guilty feeling will not produce any value to your life.
Some people are feeling guilty about for what someone else had done. In that case you have to see a psychiatrist.
If the guilty feeling is constantly bothering you, you have three options.
Correct the mistake you have done in the past if possible or compensate it whatever possible manner. Otherwise promise yourself it will not be repeated again.
Let go the guilty feeling and be released and relaxed