She wants to fast but she does not cover her face or hair
Question

I AM CURRENTLY FASTING AND WOULD LIKE TO KNOW WETHER MY FAST IS STILL VALID IF I DO NOT WEAR THE PROPER HIJAAB. WHEN I GO OUT TO WORK I LEAVE MY HEAD, NECK AND HANDS UNCOVERED BUT EVERYTIHNG ELSE COVERED.
Praise be to Allah.We advise you to adhere to complete hijaab in front of non-mahram men so that your fast will be accepted and its reward multiplied, and so that the same will apply to your prayer and the rest of your good deeds. If a Muslim woman fasts but does not wear hijaab, her fast is still valid, but she is sinning by neglecting hijaab. Being uncovered does not affect the validity of one’s fast, but the one who displays her beauty and adornments (tabarruj) is threatened with punishment from Allaah for going against His commandment. We advise you to obey the commands of Allaah (interpretation of the meanings):
“…to draw their cloaks (veils) all over their bodies…”
[al-Ahzaab 33:59]
“…and not to show off their adornment…”
[al-Noor 24:31]
“…and to draw their veils all over Juyoobihinna (i.e. their bodies, faces, necks and bosoms)…”
[al-Noor 24:31].