Thank you for posting your query in Microsoft Office Community.
Please provide additional information to help you better.
1) Why are you trying to re-install the Office suite?
2) Did you first try uninstalling the existing Office installation and then try re-installing it?
If you're unable to uninstall the existing Office suite, I suggest you to run 'Fix it' from the following article to remove the traces of Office and then try re-installing it. http://support.microsoft.com/kb/2739501
Note: Save the ‘Fix it’ before running it if you’re working on a 64 bit Windows.