What should a girl do who has been accustomed to stealing since childhood, feels that it has become a habit for her, fears that her prayers will not be accepted, feels distant from God, cannot return the stolen items now, and is ashamed to repent because she does not feel complete remorse?

Since you know that consuming unlawful earnings is an impediment to prayers being answered, you should have abandoned consuming the unlawful rather than abandoning prayer. For the non-answering of prayers due to unlawful earnings is not always a necessary outcome. If you are unable to return stolen goods, you must resolve to return them when able, not to revert to stealing. For repentance is accepted no matter how great or repeated the sin. Allah says: "Indeed, Allah loves those who constantly repent." And Ibn Kathir said: "Meaning, from sin, even if its commission is repeated." And Allah says: "Say, "O My servants who have transgressed against themselves [by sinning], do not despair of the mercy of Allah. Indeed, Allah forgives all sins. Indeed, it is He who is the Forgiving, the Merciful."" Therefore, you must hasten to repent by desisting, regretting, resolving not to return to sin, and returning the stolen goods or seeking the owner's forgiveness. If you are unable to return them, then you must resolve to return them when you are able.