It may be a bit more serious than Aerobelly's suggestion. I had the same issue with both Excel and Word a few months ago, although PowerPoint was not affected. I think it was because something in the registry had got corrupted.
Some suggested solutions said I could start up Microsoft Office in its safe mode, and go from there. That wouldn't work for me and I ended up going into the registry and doing some edits to solve it - having backed it up first if course. On rebooting, the registry rebuilt itself and it was worked OK ever since.
Try doing a search for the exact error message you are getting, and you will find lots of others who have had the same problem. Lots of suggestions what to do, but not everyone was able to solve it the same way. Try all the other ones first before editing the registry!
Also can you copy the xls file to another known good pc and try opening it from there - just to eliminate the possibility of the Excel file itself being faulty? Can you open up other Excels and Word docs successfully?
Good luck.
Last edited by tow1709; 3rd July 2016 at 08:53.