Can’t edit my files using MS OFFICE

I was doing some office works yesterday via Microsoft Office and my laptop suddenly alarmed me of low battery consumption so I saved my works immediately and let the laptop close for a while to have it charged.
When I turned it back on I can’t seem to edit my files anymore using MS Excel.
I tried my other files in MS word and I can’t seem to edit it also. What could be the cause of this?
All replies will be very much appreciated. Thanks!
