Don't rush into expensive data recovery before you've established beyond doubt that some software won't recover the data.
You must slave it to another machine via the ATA bus directly. Then see if that computer can see it. That way you rule out other problems with the original computer. If the drive can be seen but the data or partitions are missing then you can try something like GetDataBack to analyse the disk for partitions and data.
If Windows cannot see it then check in the BIOS of the computer you slave it to, to see if it shows up in BIOS if it doesn't then you're probably going to need help