I´ve been working with KiCad for some weeks (5.1.8) and everything worked fine.
Today, I made some changes in eeschema. Then, it chrashed and cannot be started again.
I already rebooted my PC, de-installed KiCad, cleared the registry and then re-installed it.
eeschema does not start. It is shown in the task monitor, but the window is not visible.
PCBnew and KiCad itself (starting page with project selction) seems to work.
First Edit your first post (by clicking on the pencil icon, and then add the full version info from: KiCad / Help / About / Copy Version Info and paste it below your post.
Recently there was a post with an issue that looks a lot like yours:
Is it the same, or does it just look similar?
His workaround was to go back to KiCad V5.1.7.
5 min ago I found another similiar post. The recommended solution was to delete the user folder within kidcad (user folder (%APPDATA%/kicad). I copied the files and saved them in a different folder. After deletion eeschema can be started again.
If you are willing to help with finding the problem, copy each file back to the active configuration folder one by one and try to start KiCad again. At some point it fails and we would know which file causes this.
In any case you should be able to copy fp-lib-table and sym-lib table safely, they restore the missing library information.