Sorry for your loss.
It could be complicated, but all you need is a bit of research, a lot of people played around with Bitcoin early on without fully understanding it and lost access to their coins through carelessness. The simple rule to follow is 'not your keys, not your coins'. So basically having access to your private keys gives you ownership of your Bitcoins, preventing anyone else from having that access protects you from loss and backing up your private keys means you can always recover it in case you lose your device.
Private keys are represented as 'seed phrase' or 'recovery phase' which consists of group of 12-24 words. This makes it much easier to back up.

Better luck care next time.