First: if the usb-flash detect in the system Windows, then File System of usb-flash isn't correct and Windows ask you to format it, right?
So for this procedure you can try this
software pack!!! The pack have 2 tools HP-format and Flash Memory Toolkit(format, read and write test) with crack!!!!
Download this pack, choose your usb-flash in the list of device and click Erase button (Flash Memory Toolkit)... HPtools can format usb-flash and change your usb-flash file system FAT, FAT32, NTFS!!!
Second: if usb-flash detect in the OS, then it's good, try with this (see top) software format it!!! if not, then you need a firmware or tools from Ever2GO, If I have correctly understood!!!