Most likely your student azure account expired, or you used up the $100 credit. You can check its status.
if the credit is used up you can run other free services, but you will need a new subscription plan to enable the sql service. This new plan (typically pay as you go) will cost you money.
if the subscription expired, then if you are still a student you can renew once a year and get another $100
details
https://azure.microsoft.com/en-us/pricing/offers/ms-azr-0170p
note: sql serverless is a much cheaper option than an actual sql service.