In addition to steps suggested by jack4rall you need to del the files that get listed after
attrib -h -r -s /s /d g:\*.*
del g:\ [file name]
sometimes you get a message " Process completed , file sharig violation" while trying to delete a file.
In that case you can install a software called "Who lock me?" (search in the google) and install the same.
You can kill the process and delete the file. Make sure to create a folder in the file name you have deleted so that the virus may not be able to creep into the drive once again.