Nextcloudpi - how can I finde the storage after a crash?

Hello together,

I use nextcloudpi with two usb-sticks (one for drive and second for backup). Bevore I use it for daily use, I like to know how I can grab on my files, when the raspberry pi will become defect.
I tried it out so I fash a new immage on the sd card. But then I can’t finde the usb-sticks. I can only go till /media. And the command ls doesn’t function almoste bevor.

Thanks for help and ideas.
Sunny wisches