Seagate 500 GB ATA not formatting entire hard drive

How much is not being formatted?

It should format to around 465 GB on a complete format...

Windows 7 only allowed 127 GB. How do I format the rest of the hard drive without starting over?

What make/model of computer is this one? That sounds like a drive size barrier on REALLY old computers....

It's a Toshiba Satellite L355 with a dual Core Processor T2370.

Hi, get a refund if it's new and get a Western Digital

Replacing a Seagate with one from WD will not solve this problem.

I expect mavroxur is on the right track. The issue for some computers with older IDE drive controllers is lack of a feature called "48-bit LBA Support". Without it, the largest HDD you can use is 128 GB.

The limit actually is in the BIOS chip on the mobo that runs the controller. Many computers with this problem can have the BIOS updated to a new version that DOES include 48-bit LBA Support. (NOTE that just "LBA Support for large hard disks" is not enough. The older 28-bit version was in use for some time. It must specify 48-bit.) Check the Toshiba website for your exact model and see whether a new BIOS can be downloaded that solves your problem. If it can, also be very sure to find out exactly how to "burn" this new BIOS version into your mobo BIOS chip. And pay attention to the notes of caution. You must not risk running out of power in the middle of the BIOS update "burn" process.

Once you have the requisite 48-bit LBA support in your machine, you will be allowed to Partition your HDD to its full size, if you so choose, and then to Format it. BUT if you want to have all 500 GB as one Partition ("drive"), you really should Delete the existing 128 GB Partition first. That means, of course, losing all its data. So copy anything you need off the new HDD before proceeding.