|It should have come with Systems Disks by Law, unless you bought the computer used and the original user kept it. |
You will need to get your hands on a copy of office. If they did not send a disk they might have an ISO on a backup partition that you can create a disk from. Call the manufacture (i.e. Dell, HP, Sony, who ever) and get tech support. They will show you how to create a disk or how to order one.
In the mean time, is your Office Working? If not try uninstalling the calculator.