My HDD is not detecting ?

Have you tried swapping cables?

Check the jumpers, if it is set to slave, the OS will not look for a slave if it can’t find a master

It’s a SATA drive. There are no jumpers.

What’s the OS?

OS = Operating System

I believe Mr Haas would like to know which OS the OP is using.

My OS is:Windows XP

@pdworkin Bingo!

Unfortunately I went too fast and didn’t realize that the problem starts at the bios.

Seagate’s knowledge base has an entry that directly addresses your problem:
http://seagate.custkb.com/seagate/crm/selfservice/search.jsp?DocId=168595&NewLang=en&Hilite=

If that doesn’t take care of it they also have an installation and troubleshooting guide here:
http://seagate.custkb.com/seagate/crm/selfservice/search.jsp?DocId=196169&NewLang=en&Hilite=

If you bought an OEM drive you might not have their diagnostic tool. It can be downloaded from here:
http://www.seagate.com/www/en-us/support/downloads/seatools

I hope it helps.

@Jack Haas
i wiil see & let you know.
Thanks Jack

@blinkErri You’re welcome.