Media uploading error

https://www.bckorea.ca

I’ve been keep trying to upload image file on my board page.
How ever, it doesn’t complete upload and displayed on my webpage.

I installed other plugin( kind of board plugin), it also works and help to upload image and media files.

I am not sure which error appeared first, but I am face to 500 error recently during upload media file.

I am thinking about that delete word-press editor and reinstall it.
Before step on next page, wish to hear your advice and how to reinstall wordpress editor safely.