Watching a movie on external hard drive & accidently pulled the usb plug from pc, hooked it back up & restarted pc, pc not reading external hard drive now. seems like external driver not running
When USB mass storage devices are not "safely removed" problems do occur.
1 - Check the drive in disk management to see what it shows, like valid file system, status etc.
2 - Windows Restore to date prior to pulling the plug.