can you find de number of a annonymous/private call ?need help

You can only call back a private number if you pick up the phone before anyone else calls you. Dial *69

Here's more info regarding this

https://www.lifewire.com/how-to-call-a-private-number-4171640

https://www.wikihow.com/Call-Back-a-Blocked-Number

You will have to check whether Fizz supports this feature.

In any case, threatening or harrassment calls can be reported to police 911. They will follow-up.

Ken is correct, as it shows #69 in the posted cellphone pic

https://www.lifewire.com/how-to-call-a-private-number-4171640