Unable To Access Hard Drive

I have a hard drive which started giving me an error when loading windows saying Paging File missing…. Later it refused to boot and on making it a slave. When trying to access it I et the message “Access Denied”.
When i try to reinstall Windows 2000 on it or repair it using the install disk it is always i=unable to copy the systemn files ntdetect.com,ntldr and some other system files. What can i do to access the data on these drive. I have 4 years work on it.