She has put on hijaab ad repented from having haraam relationships - will Allaah forgive her

if someone who use to go out with boys and now wants to change and has asked for forgiveness and has started to wear a hijaab.will they get forgiven?

Praise be to Allaah.

Undoubtedly this action which you used to do is one of the
forbidden things which are not pleasing to Allaah.

But the Bounty of Allaah is immense and He is the Most
Merciful of those who show mercy. He is more merciful than a mother towards
her child. Hence repentance wipes out whatever came before. If a person
repents sincerely to Allaah, then Allaah will forgive him. Allaah says
(interpretation of the meaning): 

“O you who believe! Turn to Allaah with sincere
repentance! It may be that your Lord will expiate from you your sins, and
admit you into Gardens under which rivers flow (Paradise)”

[al-Tahreem 66:8] 

Ibn Katheer said, [the phrase] ‘it may be’ in the case of
Allaah means that He will definitely [do that]. 

And it says in the hasan hadeeth which was narrated by Ibn
Maajah from Abu ‘Ubaydah ibn ‘Abd-Allaah from his father that he said: “The
Messenger of Allaah (peace and blessings of Allaah be upon him) said:
‘The one who repents from sin is like one who did not sin.’” (al-Zuhd,
4240; classed as hasan by al-Albaani in Saheeh Sunan Ibn Maajah, no.
3427). Undoubtedly when the Muslim turns back to Allaah and repents to Him,
this is something which fills the heart with gladness. How can it be
otherwise, when Allaah Himself rejoices over that? It says in the hadeeth
which was narrated by Imaam Muslim in his Saheeh from Abu Hurayrah
(may Allaah be pleased with him) that the Messenger of Allaah (peace
and blessings of Allaah be upon him) said: “By Allaah, Allaah rejoices more
over the repentance of His slave than one of you who finds his lost camel in
the wilderness.” (Kitaab al-Tawbah, 4927). So praise Allaah for
helping you to repent and for guiding you to the right path. Beware of
returning to misguidance after having been guided. You have to remain
steadfast and not take lightly any forbidden thing that you did before you
repented.  Keep away from bad friends, and be patient and persevere in
doing so, because bad friends will do their utmost to hold you back and make
you doubt that Allaah has forgiven you. Do not pay attention to anything of
that kind, rather strive to draw closer to Allaah by obeying and worshipping
Him. Try to find alternative friends among righteous women so that they can
help you to follow the path of guidance. We ask Allaah to help you adhere
firmly to His religion and His way.

And Allaah knows best. May Allaah bless our Prophet Muhammad.

Sheikh Muhammed Salih Al-Munajjid