If the system came with Microsoft Office you would have got a MPI Card which contains your Office Product Key see here for details: [URL] The problem may be due to factory settings and a conflict with the Windows 8.1 Update (hence it returned). In that case clean installation of Windows 8.1 may help. See A Clean Install of Windows 8.1: [URL]
About a year and a half ago I purchased a DELL Inspirion R15 for my daughter and sent her off to college with a 3 year extended warranty. Over the last few months, she has been having wireless network issues and decided to go to her college's IT department instead of calling DELL.  The genius' in the IT department decided that the problem must have been a OS corruption from the Windows 8.1 update and they decided to reformat the hard disk and reinstall Windows 8. Of course, that did not solve the problem and the laptop is now back in my hands.  I called DELL technical support and the WiFi card on the laptop will be replaced as soon as the part arrives. Now my question... The laptop no longer has the Microsoft Office package which I purchased with laptop and was installed when the laptop was delivered. By using the Recovery disks that I created on day one, can I reinstall Microsoft Office?  If not, how do I get the software back on the laptop?
Recovery Disks and Recovering Microsoft Office