Forgotten password

The reason you lost your data was that you failed to backup your device.

You should look to backup your device regularly (You can even set it to do so automatically overnight via iCloud) to avoid losing data in case a similar incident happens again

Please follow the steps at the link below for help backing up your device:

How to back up your iPhone, iPad and iPod touch – Apple Support (UK)

nuria1301 wrote:

I can't believe I had to erase all my data

That’s exactly the reason to keep a current iOS backup. Restore that backup to retrieve your data.