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.
For the last 2 weeks I have become consumed in restoring my lost programs once I upgraded my wind 7 to wind 10 on my laptop. I get no help from my laptop manufacturers, HP, as their response is that since I purchased my Pavillian 6 in 2011 my extended warranty is even expired and they want me to purchase their tech support plan for only $300 plus a year. Don't they realize that for a little more I could purchase a new laptop and toss the non-functioning HP one. Since my office came installed in my laptop I don't have the option to reinstall the office with a disk. MY QUESTION: Is there any free downloads to recapture my original word starter 2010? As an interim option I have been able to install Word Perfect 11 from a disk that came with an old desktop PC. But I'm sure this will last for only a short while and it will be outdated. I sure hope other Microsoft users don't follow my mistakes of upgrading my wind 7 to wind 10. I probably wouldn't have even considered the upgrade if it hadn't been for the problems I experienced when Windows XP phased out and I didn't upgrade before it was too late and I ended up with a desktop (DELL) even after installing additional memory to accommodate the move to wind 7 that was useless and now sites alone in my home office as a reminder of that fiasco. And now I'm hearing that we all are going to be forced to upgrade to wind 10 after June 2016, REALLY?