files appear to be "hidden operating system files"

hii, i'm very new to these things so sorry if i can't explain much but i'll do my best.
the thing is my system crashed a few days ago n it wouldn't start, so i got this friend of mine to format my C drive, now dat is done, the only problem is i can't view my files on D drive unless i disable the 'hide protected operating system files'. i see all my files when i disable the feature, but i can't change them to unhedden file in the properties menu of the files as it is faded out!!

can any one help me out on this?

i am desperate to get my file bank and would be very gratefull to any one who helps

thank u