Topic: SD-card in iris Book2 doesn´t work correctly after deleting files

Excuse me please:
I am new and can speak only a little English. I found this page by asking for a correctly Deleting files of any SD-card for iris book 2 (a mobile scanner).

First the iris-book-2-scanner scanned correctly. Then I deleted some files in the micro-sd-card of the scanner on PC. Now I couldn´t more scan.
I formatted the micor-sd-car in the scanner, and I could scan again.
My Qustion: Where /how can/shall I delete correctly some files on then micro-sd-card?

Thank you very much!!