unplug your USB
Go to run and type this
gpedit.msc
Navigate to computer configuration - Administrative
Templates-System, and then select Removable Storage Access in the left
column
on the right side
you may find something like
Removable Disks: Deny execute access,deny write,deny read access,
all removable storage deny
open them and disable all these four options.
Plug in your USB ,it should work now.
