My 4gb reads write protected, i cant send or delete the files

click start control panel administrive tools computer management disk management right click on your drive select properties then security select take full control in windows 7USB drives can be write-protected by modifying the StoreageDevicePolicies Registry key and WriteProtect Registry value.
click Start>run>regedit to open Registry Editor. and press control+F to open the find dialogue box and type "usb device" or "driverdesc" to open usb mass storage device or type "usb mass storage device" in the search windows. And right click on it and delete. This will set the policy value to 0. then insert your usb device. It will work fine.
# Remember: do not delete any unknow files in the registry as this will make some programes not work as usual.

also
If you are running a Windows XP OS then you might be able to:
- click start right click on my computer select open
- Right click the icon of your Flash Drive (It should be F:/ or something)
- Click Properties in the menu that comes up
- Click the Sharing tab
- Click permissions
- And finally, click Allow next to Full Control.
hope this helps