How can I fix the message "USB storage damaged"?

Hello everyone!

Sometimes, after I turned off then on my phone, I get the message "USB storage damaged". All applications, such as photos, videos and music can't be used.

In somes cases, the problem just disappears after few days, during which I usually just ignore the phone.

But most cases, the problem remains and I must format the USB, lose all data, and then it works again...

I'm wondering:

1. How can I fix the issue without formatting？

2. How can I prevent this from happening?

Thanks in advance for all constructive answers.

D