There are many reasons this could happen, from new Windows Defender settings blocking Kodi processes, to you possibly updating Windows with a Local file, and not getting the latest Service Pack or Security updates available.
Here is a link to Kodi install info for Windows;
Code:
https://kodi.wiki/view/HOW-TO:Install_Kodi_for_Windows
Here is a direct link to Kodi's download page for Windows;
Code:
https://kodi.tv/download/849
Recommend you ensure your version of Windows os is up to date, and you have 32 or 64 bit machine with the corresponding 32/64 bit version of Kodi.
Then I would just re-install Kodi (if on Win 10, you should install from the Windows Store, if possible)
/Shooty