Here in Algeria a lot of women thought that feet are not forbidden to show them in the prayer or in markets, is any Fatwa exist for this?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.

A woman should cover her feet when performing the prayer. The majority of the scholars are of the view that it is a condition for the woman to cover her feet in order for her prayer to be valid. Abu Daawood reported that Um Salamah asked the Prophet : "Can a woman pray in a garment and a veil without a lower dress?'' The Prophet replied: "If the garment covers down to the front of her feet". [Al-Haakim]

Imaam Maalik, Al-Shaafi'ee and Imaam Ahmed (in one narration) are of the view that it is obligatory on a woman to cover her feet when performing the prayer. It is also forbidden for the woman to reveal her feet in front of non-Mahram men (those whom she is Islaamicaly allowed to marry), because the feet of a woman are a part of her 'Awrah (parts of the body which must be covered Islaamicaly) before men other than her Mahram (non-marriageable relatives). The evidence regarding the above is the saying of the Prophet : "On the Day of Judgment Allaah will not look at the person who drags his garment with pride and arrogance", so Um Salamah inquired: "What should women do with their lower end of their dress?" The Prophet replied: "They should extend it the length of a span of a hand." She said: "Their feet will thus be exposed?" Thereupon the Prophet said: "So they should extend it the length of a cubit and should not extend it further than this." [At-Tirmithi and An-Nasaa'ee]

Therefore a woman should be very cautious about revealing their feet, whether in the market or anywhere else. When a Muslim woman goes out of her home, she should be properly and modestly dressed covering what Allaah has commanded her to cover, not wearing perfume and not being exposed to the sight of men but she should be shy expressing signs of her chastity.

Allaah knows best.