I have done a clean 32 bit Win 7 install over a previous 64 bit install on the C partition. The Da partition was not touched but now is inaccesible as is my external USB hard drive. Both are NTFS and up until yesterday had no errors or problems. It is a 64 to 32 bit problem or access permissions? Thank you for any pointers as to how to cure this!!
Thanks for the pointer, but the problem was a bit more fundamental. After some investigation I discovered that having only reformatted the C drive not the D, I no longer had the correct access powers, I changed these and I could see the files. As regards the external drive I think I must have unplugged it while it was working so messing up the file index. My son's Mac could read it though so I copied off the relevant files and reformatted the disk. All is good now thanks PudgyChicken!