my machine XP was continuously rebooting upon turning it ON. I booted through XP CD- recovery console and c prompt came instead of c:\windows>
booted again from XP CD selected install XP-F8 and msg dispalyed was C: drive unformatted partition.
Again booted from XP CD ran DOS commands fixmbr and fix boot. result after F8 it shows 2 partitions of FAT 10 MB and 32 Mb whereas the HDD is 120 GB.
Ran testdisk a tool for securiing lost partitions and recover boot sector but it could not detect.
what must I do next to secure and recover boot sector/ MBR/ partition tables?
"what must I do next to secure and recover boot sector/ MBR/ partition tables?"
It may be more serious than that, Sanjay. You first need to test the hard drive with the drive manufacturer's diagnostic software to ascertain if the drive has failed. The download links are here: http://www.tacktech.com/display.cfm?ttid=287
The software you download must be a DOS version that runs from a bootable CD. The download will be an ISO file.
From this ISO file, you can create a bootable CD using IMGBURN from here: http://www.filehippo.com/download_imgburn/
When you've made the CD, boot your faulty XP machine from it to test the hard drive. Use the long or extended test if such a test is available.
@sunjai, I have experienced the same problem personally.
Microsoft's FIXBOOT malware has trashed your boot sector. Why any braindead programmer would replace the boot sector on a 120GB HDD with a 10MB FAT12 boot sector is completely beyond my understanding, but that is what has happened.
If I were approaching this problem, I would first investigate the extent of the damage with a disc editor in readonly mode. For example, you could use DMDE to search for backup copies of your original boot sector(s). Select Tools -> Search For Special Sectors.
Otherwise, I would clone your drive with a tool (eg ddrescue) that understands how to work around bad media, and then use data recovery software on the clone. I would prefer a manual repair because automatic repair tools can't always be trusted, as you have witnessed firsthand. BTW, avoid using Microsoft's CHKDSK to repair your file system. It often makes the problem much worse. CHKDSK is OK in readonly mode, though.
BTW, +1 to phil22. The root cause is probably a physical one.