If the worksheet is protected and the cell you are trying to enter it also
protected then you can not enter data. click on Tools - Protection and see
if you can unprotect the worksheet. I would ask whoever gave you that file
first if you can do it.
Now when you say blank worksheet are you talking about a blank worksheet
within the same file? If so then it is also protected.
Or are you talking creating a new xls file and still can not enter data? Are
you using the ten key pad and num lock is not lit? If you cannot enter
anything on a new file then you need to reinstall excel.
