I'm amazed it disappeared during the upgrade. Maybe you did a clean install?

If you really did an upgrade from 7 to 10, you have 30 days to go back. That should restore everything, including Office. The alternative is to go back to factory conditions from the recovery partition or from the disks that came with the laptop or that you made yourself.

http://www.techspot.com/downloads/downloadnow/6255/?evp=eb1291cdb3862ab973d14e63edfce787&file= is a very unofficial download link. But it says it's only for Windows XP and 7, not for 8 (and so probably not for 10 also). Use at your own risk.

Or switch to another word processor. For example a current version of MS Office, or the free Libre Office.

PS. You're not forced to upgrade. If you prefer to keep running Windows 95 or whatever version you are happy with and you have a PC that runs it, that's no problem at all.