One time I put my attention to my PC which kept on restarting .I assumed it was full of dust so I opened the case and blew the dust off.It was really full of thick dust.But when I put everything back I found out hd's led did not come on and there was no single sound I could hear.The monitor shows the "intel desktop logo " in blue screen and then stops after few seconds the monitors led turns orange.
When I checked the RAm it was fully seated as well as the IDE cables connectiing the hd to motherboard.
I was not only sure if it shoould be plugged into white ide slot which is the second slot or the one that comes first.I even unplugged floppy disk drive and the cd drive frm the mother board to check if it wll work but remained the same.CD was coming on even if it's IDE cable was not connected to the motherboard.I was wondering why.Pls tell me how to put the hd back to its position properly.It was booting normally before the prob was that it kept on restarting randomly/Thanks for your suggestions.

Recheck your IDE and molex connectors. The two IDE connectors on the motherboard are usually seen looking from left to right down on them as primary and secondary. The hdd is usually plugged into the primary location. If you have power to the hdd and the IDE cable is in good repair and connected properly then you could have a dead hdd.

Let us know the exact make and model of your system (or the motherboard if it was custom built) and we'll be able to provide more specific suggestions.

Usasma, Im sorry for the delayed response.

Here's this PC's specs:

System Mnufacturer D815EW
System Model EW81510A
Processor x86 Family 6 Model 11 Stepping 1 GenuineIntel 1129 Mhz
BIOS version/date Intel Corp EW815150A.86A.0044.P03,10/16/2001
SMBIOS version 2.3
Total Physical Memory 128 mb(PC133)
Cache Ram 256


Thanks.

Not much info is available for your mobo. I'd suggest looking carefully at the motherboard to determine which of the two slots for the hard drive is primary, and which is secondary. You may be able to find this information out in the BIOS by looking for where the current hard drive is hooked up to.

Please ensure that the computer is unplugged from the wall and that you're grounded on the metal chassis of the computer while messing around inside the case.

Next, try another ribbon cable in place of the current one. You can usually get them cheaply at a small computer repair shop.

Then:
1) Reseat the cable where it plugs into the motherboard
2) Ensure that the jumper settings on the hard drive correspond to where the cable plugs into the hard drive (If on Master, then the far end of the cable must be plugged into the hard drive - if on Slave, then the middle connector must be plugged in - if on CS (cable select), I'd recommend plugging it into the end but it's not required).
3) Ensure that it's seated properly, and then ensure that the power connector is also seated properly.
4) Fire up the system and check to see that the hard drive is actually running (you can hear or feel it by gently touching the side of the drive).
5) If all that works, then I'd suggest trying a free diagnostic from the manufacturer of your hard drive to see if it has failed.

Yes, I have prepared Seatools, a free diagnostic tool for dos from seagate, but I just couldnt figure out how I am going to use it.I stored it in a floppy disk as I thought this should be run in windows mode.
But when I booted the PC from bootable disk and ran seatools, it was saying that the program can not be run in dos mode.Kindly should me the way how to use this hd tool.Thanks.

And may I know if the BIOS version installed on this PC can be upgraded?May be this requires flashing of new BIOS.What do I need to know?With small details I gave you, do you think this will work,or will this most likely damage the motherboard more severely?

Since the floppy tool isn't working for you, I'd suggest trying the ISO CD-ROM image. Burn the image (not the file) to a CD using an free ISO recorder utility ( one is at http://www.deepburner.com ). An ISO image is laid out so that when it's burned to the CD, the boot files are located in the proper location (that's why the special tool is needed).