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 Allaah 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 Allaah 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 Allaah for what they have done, and Allaah is Forgiving, Most Merciful.