Firstly: 

There are essential pillars and conditions for marriage which must be met. That includes the guardian of the woman and two witnesses. If there is no guardian, two witnesses and publicising of the marriage among the people, then it is not valid. 

If only the guardian is missing, then it is not valid according to the majority of scholars, but it is valid according to some fuqaha’. 

If there are no witnesses, but it is publicised among people, this announcement is sufficient according to some scholars. 

The guardian of a Muslim woman must be a Muslim. Her guardian may be her son if she has one, then her father, then her grandfather, then her brother, and so on among her relatives on the father's side, the closest then the next closest. If she has no Muslim guardian, the Muslim judge may conduct her marriage if there is one, otherwise the head of the Islamic centre and the like may conduct her marriage, or a man of good character among the Muslims may conduct her marriage with her consent. 

The woman must have a dowry even if it is little. If the dowry is not mentioned in the marriage contract, the marriage is valid and she is entitled to a dowry like that of her peers, meaning that she is to be awarded a dowry that is equal to the dowry of her peers among women in her country. 

Whether your marriage is valid or invalid, the dowry is your right and if you have a child he is to be attributed to his father. 

In the event that the marriage is invalid because there was no guardian or witnesses or announcement, you have to keep away from this husband until a new and valid marriage contract is done. In that case the marriage must be documented and registered in the Saudi embassy in your country, so as to guarantee your rights and the rights of your children in the future. 

Secondly: 

The husband is obliged to provide suitable accommodation for his wife and to spend on what she needs. He does not have the right to leave her in a country where she is not safe, and he does not have the right to be away from her for more than six months except with her consent. If he has finished with the purpose for which he came to the country in which he got married, whether it was business or study or anything else, and he wants to go back to his original country, then he must take his wife with him and at least provide her with accommodation in another city, other than the city in which his first wife lives, until he has the chance to tell his first his first wife about his new wife. 

If he refuses to give her her rights or take her with him, and he wants to leave her in her country where he married her – for longer than the period that we have mentioned -- and she does not agree to that, then she has the right to ask for divorce. 

What we advise Muslim women who live in countries like yours and what we advise their guardians also, is not to rush to do and take their time before agreeing to any marriage, and to find out precise details about the situation of any stranger who wants to marry their daughters and is living in their countries for any purpose, whether it is for study or business or tourism and so on. Many of these people, very many, are not serious about marriage and they do not want to take a solemn covenant on which to build a family; rather all they care about is fulfilling their desire right now, then when they have finished with their business they leave the country and they leave behind a wife and maybe children too, if they have children. “and Allaah will inform them of what they used to do” [al-Maa’idah 5:14]. 

And Allaah knows best.