Unity player as in a web player? I don't normally play games via browser. It's slow and your save games are managed by the browser. They can easily get deleted if you clear the cache. Regardless, try clearing the cache of your browser first. If you don't know how to do that you can google it by [Your browser] + how to clear cache. If that doesn't do the trick, start disabling privacy and ad-block related browser add-ons/extensions.
If that still doesn't get the game running then there's probably two things left to do:
1. Try running the game with a different browser.
2. Download a copy of the game and start it from your computer. Which is something I always recommend. These games run much smother on your local PC instead of relying on itch.io's servers.
Edit: typo