Does masturbation affect the hymen, and what should a twenty-eight-year-old girl do who refuses marriage for fear of discovering damage to her hymen due to her past masturbation?

You have done well by repenting from the bad habit that caused you distress. Do not reject a suitor because of your doubt or certainty about the rupture of the hymen, and you are not required to inform any suitor about it. It is not permissible for you to consult a doctor to ascertain this, nor to repair the hymen. Conceal it and accept a suitor whose religiosity and character are pleasing. If the hymen is ruptured, mention a reason for it, as there are many reasons for this.