How to Disable /Enable Access to USB Port:

Step 1:
press win key + R
then type regedit

step 2:Located this
HKEY_LOCAL_MACHINE

>SYSTEM
>CurrentControlSet
>Services
>USBSTOR

Step 3:
in right panel select START

Step 4: To disable USB port access
type 4 in >

that box
n select hexadecimal.
click on OK
n quit registry editor

Step 5:
TO ENABLE IT:
Follow above step upto step 3rd
Now double click on START:

Type 3 in that box (to enable)
click ok

.