You have to buy Microsoft Office.
There are free downloads for word processing and spreadsheets but I have never used them.
MS Office is retailing for around $125 - $129 for use on 3 computers. This is the "home version". The Professional version which also includes Outlook is around $249 for one computer.
We recently had a computer die on us. Backups were sufficient but on numerous CDs and USBs (well, we hope they were sufficient, we did not use them). We were able to retrieve the data directly from the hard disk. If the data loss is causing problems, I suggest you investigate whether your data is recoverable.
Marg