When i open my hard drive i get a message that drive is not accessiable the file or directory is corrupted and unreadable how can i fix this problem?

there can be many causes for that depending on cause the fixing has many ways.

example :-

if you get this message last when you accessed some file in the directory which might be corrupted then open MS-DOS and see the files in the directory ... delete the file that's got corrupted and restart the computer . This must help but as i already said solution can be more easily found when cause is known first.