To add what information Mary gave you, the items removed by Dell Update can be found here.  From what I gather, there were some problems with security certificates that Dell installed on their computers to help their software run.   Regardless, follow Mary's instructions to in-place re-install Office 365 and you should be good.  I'm not sure how those certs could have fumbled something up with Office. 
Hi,My system is a 'Inspiron 7548' running Windows 10 (since July last year)and on this system 'Dell Update' ran on 13/06/2016 6:13 pm for 'DSD Cert Removal'and 13/06/2016 6:11 pm for 'eDellRoot Removal'both these list the only program affected as 'Microsoft Office 365'and I got this information from the system restore points. Since then Office is completely dead - Word, Excel, Outlook all die with'Microsoft xxxx has stopped working' Attempts to restore through these restore points all fail. Questions1. How do I get my office software back ?2. What business has Dell Update with Office in the 1st place - its not a driver or anything ? Ideas ? JC 
Dell Update has destroyed Office 365