Hi, sorry if this is a bit late, but i have had this problem on my external hard drive as well, being a teenager i was curious to try different things out, first i went into command prompt (run>cmd) and typed help, this brought up a list of options, first i tried to recover the data on the disk because i thought that i had lost it, as this was going through it stopped and told me to run the CHKDSK command to check for errors on that file so this is what i did and the hard drive works fine now
CHKDSK /F (volume path name/letter):
CHKDSK /F G:
Hope this helps