What is the ruling on the money that was spent on me from the inheritance after my father's death, knowing that my father wrote a contract before his death stipulating that he would cover my studies, and has this contract become void with his death or is it considered a will, and is it permissible for me to give up my share of the inheritance in compensation for my siblings, and am I obliged to repay these funds?

If a father committed to covering your study expenses during his lifetime, this is a gift that terminates with his death, and the money then belongs to the heirs. If the father bequeathed this after his death, it is a bequest to an heir, which is not enforceable unless approved by the adult, mature heirs, and it does not apply to the share of minors. What your older siblings spent from the inheritance money on your studies, if it was with the intention of being reimbursed, then they have the right to claim it; if it was a donation, then they do not. The share of your younger siblings is not included in this; because the money of minors may not be disposed of except in what benefits them.