I cannot Start Windows XP or reinstall a Fresh Windows on my Hard Drive or Format/delete Partition.?

I have Windows XP on my Laptop. It stopped while I was working. I have tried all sorts of things but no use. When the computer starts the Window XP logo comes on then it starts to do scandisk. It does up to certain percentage and hangs up, every time I boot it. I tried to go into safe mode; it reads few files and then hangs up. I tried to go into last known good point but no use. I tried to reinstall the fresh Windows but failed. When I try to delete the partition it does not delete it. I tried to format it in DOS with the command Format and tried with Fdisk, but failed to delete the partition. I tried the Hard Drive to connect to another computer by using caddy. It reads the files are there but does not open all of them. I tried to copy some files, it copies some of them but not all. I tried to delete the files, but it does not delete. I tried to defragment but no success. I tried to format it in Administrative Tools but failed. I tried to delete partition in it no success. I tried to format it in DOS in other computer but no success. Anyhow, I tried every thing possible but it is still the same. When I put the Hard Drive back into the Laptop it is square one. Please help for a solution, I will be very grateful. M Aslam Javed, London, United Kingdom