I need to activate my copy of Windows 7 Enterprise

PLEASE PLEASE PLEASE

Okay, now my computer originally came with Win 7 Pro OA 32 bit.  Can I download Win 7 Pro OA 64 bit and use my product key?  Or will it only let me go back to 32 bit?

Individuals cannot activate Windows 7 Enterprise - this Edition of Windows 7 is only supplied to corporate subscribers who carry out activation using special tools & procedures.

You need to reinstall the Edition of Windows 7 that is identified on the Certificate of authenticity [CoA] label on your computer casing or, for many laptops, inside the battery compartment.  Only that Edition can be activated using the Product key that you will also find on the CoA label.

If you do not have a product key on a CoA label then you would seem to have never bought Windows 7.  You cannot buy a Genuine product key on its own and anyone offering you one would actually be selling you a counterfeit, a stolen one or a not-for-resale one.  You will have to be very careful about who you buy from as there are many crooks out there and you would not want to spend money only to find it gets identified as an invalid copy later on [when you try to activate it / in a few months / in a year or more].

If you do already have a Product key on a CoA label then you will need to get a re-installation DVD for your Edition of Windows 7 unless your computer maker has already provided a DVD or some other means of installation such as a restore-to-factory facility. 

1. Amazon now stock reinstallation DVDs for only a few quid [the link is for their UK website, the US site & their other international sites also stock them].
2. These appear to be exactly what they claim to be as they do not include a product key and they are specifically described as being for reinstallation only - in other words, they are not an attempt to distribute pirated Windows.
3. You would use the Product key on your Certificate of authenticity for activation.  Reinstalling from these generic reinstallation disks will not allow self-activation [only branded reinstallation disks from your computer maker can do that].
4. Make sure that you order the Windows 7 Edition {Home Premium etc} that is identified on your Certificate of authenticity.
5. Some of the sellers provide both 32 bit and 64 bit DVDs whilst others only supply one or the other.  So make sure that you order the right type.
6. These disks can do everything that a System repair disk can do so you will not need to make one separately.

Windows 7 downloads are not available.  That's why I suggested the Amazon reinstallation disks.

Product keys are valid for both 32 & 64 bit installations but if the computer maker only installed 32 bit I would expect that to mean that only the 32 bit version could run.  I think you need to check the computer specs & ability to run 64 bit OS on their website and also on any user forums that they run.

When all this is done, you would face the prospect of an involuntary Windows 10 installation.  Prevent this using the fix I suggest in Disable Windows 10 upgrade.