A girl whose husband went out abrod for earning money,what should she do when she needs sex?in islam

In any religious faith, she just waits on husband, no one "needs" sex, they want sex.

From what I have read, she should find something to occupy her mind and body. Prayer, taking care of the home and family, hobbies, etc. are activities that I have seen mentioned.

It is my understanding that maturbation is not allowed. However, I am not certain if writing down thoughts and feelings to share with her husband is or isn't.

It may be a question for her to ask an elder.

''If a man's patience is stronger than his whims and desires, then he is like an angel,
but if his whims and desires are stronger than his patience, then he is like a devil.
If his desire for food, drink and sex is stronger than his patience, then he is no better than an animal."
- Ibn Qayyim al-Jawziyyah