Restoring your laptop or PC to factory settings is something you might want to do if it’s full of malware or viruses, or simply because you want to sell it on or give it away. However, this process will wipe not only all your files – music, photos, videos and documents – but also any programs you installed after getting the laptop out of its original box, including Word, Excel, PowerPoint and other Office apps..
Microsoft Office isn’t part of Windows as many people mistakenly believe. Unless they were already installed when you first got your PC, they will be gone if you factory reset it.
How to reinstall Microsoft Office
In order to restore your laptop and keep Microsoft Office, you will need at least the original product key, also known as an activation code or serial number. It’s usually 25 digits long.
If neither of these programs recover your Office key, it's well worth trying Recover Keys which can extract keys for over 6,500 programs. It costs $29.99, but does a much deeper scan of your PC and can retrieve keys which no free application can, including Adobe Creative Suite.
Be sure to do this BEFORE you restore your laptop, of course.
The second thing you need is the installation media, which is typically a CD or DVD. However, if you’ve lost this, or your laptop doesn’t have an optical drive, you’ll need to obtain the files another way.
Fortunately, Microsoft makes this relatively easy. So, to start with, head to Microsoft's website and click on the relevant download link. You’ll be asked to enter your 25-digit product key to verify you own Office.
If you had Office 2007, you can try this link
Or for Office 2010, try this link