What is my legal share from the sale of the house that I contributed to purchasing and furnishing for my parents, knowing that its value has changed since the time of purchase, and what is the ruling on what I spent to furnish the apartment after my father's death?

If you contributed to the purchase of the house as a donation, you are not entitled to reclaim what you contributed. However, if your contribution was with the intention of partnership, then you have a share proportionate to your contribution. If it was with the intention of recovering the amount, then you are entitled to that. As for what you spent on finishing the house, if it was not a donation, you are entitled to recover its value. And the furniture you bought for the apartment is your right and does not enter into the inheritance unless you donate it.