Windows 7: Original hard drive not seen, can't format

A shop installed a bigger hard drive with Windows 7 on it. My old hard drive had XP. They thought I could use the old one after they took my files off it but when I picked it up, they said the computer couldn't see it and I should reformat it and gave me instructions. I see the old one in Device Manager (not in Explorer) but there is no file system listing (it was NTFS). When I right click on it to reformat, the only option is delete. I would like to use the old drive for storage but can't figure out how to format it or assign a drive letter to it.
I'm grateful for any suggestions!
Christina

Welcome
I think that these instructions from MS, may help
Change, add, or remove a drive letter
Same for Seven.

Thank you for the suggestion - unfortunately, everything except delete is still greyed out.

One option would be to prep the drive for use with the free HDD diagnostics from the HDD manuf. site...use it to create a bootable CD and run it from there.

My daughter suggested downloading a partition program which I did and was able to format the old hard drive. It says the drive is good. I gave it a letter but I still can't see it in the new hard drive except in device manager.

Try low level formatting the HDD and then do a regular format. HDDGURU: HDD LLF Low Level Format Tool

i installed windows 7 and had a my old vista hdd. I couldnt delete or format it properly even tho it showed up in the admin tools and in explorer. In the end i had to use a program called Erase hard drive by Active@ KillDisk. Low Level Format. to format it.

cbrundage,

If you boot into the bios, then:
do you see the drive? yes/no

DiskPart is a powerful program that comes with your Win 7.
I will give you instructions on how to use DiskPart.

The objective here is to see if DiskPart sees the drive.

Incidentally, forget all of that "low level" format stuff. That belongs to the dark ages of hard drive hardware.

To start DISKPART:

WIN | type CMD | do NOT hit ENTER | CTRL + SHIFT + ENTER keycombo | ALT + Y

WIN=key with the microsoft logo on top

You are now running cmd.exe with administrative privileges.
This is what is called an "elevated" command prompt since your privileges for cmd were elevated.
Even if you are logged on as administrator, you still must "elevate".

Now type, and hit ENTER
DISKPART
this puts you in the diskpart program which has its own little set of commands.

type, followed by ENTER
LIST DISK
that will list the disks found

type, followed by ENTER
SELECT DISK 0
that selected the first disk in the list

DETAIL DISK
this will give more info about the disk

SELECT DISK 1
DETAIL DISK

and so on soforth for all the disks that were shown when you said List Disk

You can use
EXIT to exit DiskPart
and
EXIT again to exit the command shell

Questions are:
did your old disk show up?

If your old disk showed up, then I'll give more commands so that you can regain use of the disk.

I recommend that you find another computer repair shop.
At least come here first, the next time you have a problem.

I have tried 5 times for my post to appear. I hope it does this time.
Thank you so much for all the instructions. I did what you said and diskpart said the old hard drive was "healthy" but there was no drive letter.
Christina

Did you try the low level formatting suggested by me and vampman05?