Thank you all, l have changed the usb flash memory and it work despite the previous usb was new and work properly on other device.
I have inspiron 17 7000 and tried to upgrade to win10 pro, but the key was not activated, so I want to make a clean install to downgrade to windows home, I used "Microsoft media creation tool" on a usb but I received error messges:"Windows cannot be installed to this disk. The selected disk is of the GPT partition style."I tried some solutions but received:"Windows cannot be installed to this disk. This computer's hardware may not support booting to this disk. Ensure the disk's controller is enabled in the computer's BIOS menu."Then I used "Dell Recovery Tool" and a new usb, but If I tried to boot from usb "Legacy External Devices" it says after restarting:  "no boot device found", and when tried "UEFI > Add Boot Option" says: "name not found".I restored default Bios setting and tried f12 but usb choice is not in the list.When restart and don't press anything it take me to "SupportAssist OS Recovery", in this screen reset is not active so I have choosed onlien "Reset and update" but "reset failed" for several times when reached 65% or less!What can I do? There is no OS on the laptop now and cannot use it !
Unable to Make clean install in any way