my apple id was linked to family sharing of another apple id user, who recently passed away. why wont my apple id let me purchase anything on itunes even though i got giftcards and redeemed them?

How old is this person? A child?

Was Ask To Buy set on this user's ID?

If this person is not a child under 13, the person should be able to leave the old family. Read this link:

Leave [/Cancel] Family Sharing - http://support.apple.com/HT201081 - How to leave a family sharing group.

If the person is under 13 then he/she has to be transferred to a different family which will require authorization from the deceased person's account. That can get more complicated:

How to request access to a deceased family member's Apple accounts - https://support.apple.com/HT208510

- Apple requires a court order.

You can also contact Apple and see if they can provide advice (we here are just users like you).

Click here --> https://support.apple.com/choose-country-region/media-services Select your country, then a product. If you don't see one that handles your issue then keep experimenting with selections until you reach one that gets you a chat session or a telephone call and get the representative to redirect you.

or:

Contact Apple for support and service --> "See a list of Apple phone numbers around the world." - https://support.apple.com/HT201232