An invalid marriage contract must be done again, even if ten years have passed
Question

 
My question is that we know that a girl’s marriage without the consent of the guardian is invalid according to the shareeah. Then there are a lot of cases where the couple have eloped and got married. My question is, if the marriage is invalid, how do these people make it valid, lets say after 5 years of marriage or 10years of marriage and they have children now.
My other question is that if a couple runs away and gets married and then after certain period, lets say 2years or 4years the parents then give consent or come to acceptance of their marriage, then is the marriage valid.
How do some one make this marriage valid?
Praise be to Allah.If a woman gets married without the consent of her wali (guardian), her marriage is invalid and is not valid even if ten years have passed and even if they have children. It is essential to repeat the marriage contract after her guardian’s approval is obtained, because the Prophet (peace and blessings of Allah be upon him) said: “There is no valid marriage without a wali and two witnesses.” (Narrated by Ahmad and the authors of Sunan except al-Nasaa’i. See Saheeh al-Jaami’, 7558).
 There is a stern warning against a woman who arranges her own marriage. The Prophet (peace and blessings of Allah be upon him) said: “A woman should not arrange another woman’s marriage and a woman should not arrange her own marriage, for the zaaniyah (adulteress) is the one who arranges her own marriage.” (Narrated by Ibn Maajah, 1782; see also Saheeh al-Jaami’, 7298).
 With regard to the second question, which has to do with the approval of the wali; in this case it is essential to repeat the marriage contract, because the first nikaah was not valid. The couple must also repent sincerely to Allah for what they have done, and Allah is Forgiving, Most Merciful.