Sometimes when you reinstall windows the customer can not find their installation CD. Assuming the computer can boot and all you need to do is reformat. Then you can use the program
to locate and write down their existing Microsoft Office serial and which version of Microsoft Office they had. You can then use one of the links below to download a trial version of Microsoft Office that corresponds with the version they had. Then during the installation use the key you wrote down to install and activate the product.
Microsoft Office 2003
Microsoft Office 2007
Home and Student
Microsoft Office 2010
Microsoft Access 2010
These are the only links I could find. If you could provide other links to even more Microsoft Office Products that would be great and I will add them to the list.