He owes many expiations for breaking oaths (kafaarat yameen) but he does not know what some of them are
Question

                I owe many expiations for breaking oaths, some of which I know and some I do not know, because I often swear to do something then break that oath. This has become a habit with me. How can I expiate for that even though there are many of them?.
Praise be to Allah.What is required of the 
      Muslim is to take the matter of oaths seriously, by not swearing many of 
      them. Allaah says (interpretation of the meaning): 
“And make not Allaah’s 
    (Name) an excuse in your oaths”
[al-Baqarah 2:224]
So do not swear oaths 
    except when necessary. The Muslim must protect his oath by offering 
    expiation if he wants to do something other than what he swore to do, 
    because the Prophet  (peace and blessings of Allaah be upon him) said: 
    “By Allaah, if Allaah wills, I do not swear an oath and then see something 
    that is better than it but I offer expiation for my oath and do that which 
    is better, or I do that which is better and offer expiation for my oath.” 
    Narrated by al-Bukhaari and Muslim in their Saheehs. This version was 
    narrated by al-Bukhaari. It was also narrated by Abu Dawood, al-Nasaa’i, 
    al-Tirmidhi, Ibn Maajah and Imam Ahmad. 
With regard to numerous 
    oaths, if they all had to do with the same thing, then expiation only needs 
    to be offered once. For example, if you said, “By Allaah, I will not speak 
    to So and so,” and you said that many times, then you spoke to him, then you 
    only have to offer expiation once. 
But if you swore oaths 
    regarding several things, such as if you said, “By Allaah, I will not speak 
    to So and so,” then you spoke to him, and you said, “By Allaah, I will not 
    travel to such and such a place,” then you went there, and so on, then for 
    each oath you have to offer expiation. And you should try to be on the safe 
    side by offering expiation for whatever you think is most likely to be the 
    case, so that will have discharged your duty. 
And Allaah is the Source 
    of strength. May Allaah send blessings and peace upon our Prophet Muhammad 
    and his family and companions.