Unless you provide a link to a page demonstrating the problem, no one will be able to offer much in the way of assistance.
I was able to get the image inserted by changing to text mode then inserting with the img icon. I then coped the path of the image and pasted there.
It would still be nice to get “Add Media” tab to work in visual mode.
If the add media button is not working it may be that there is a javascript error. In Chrome, press control-shift-j to bring up the console. Then clcik add media. Any javascript errors will be highlighted in red in the console.
Either way it sounds like you have a corrupted install. To debug:
Deactivate all plugins to see if this resolves the problem. If this works, re-activate the plugins one by one until you find the problematic plugin(s).
Switch to the default theme TwentyFourteen to rule out any theme-specific problems.
Sometimes, an apparently inactive plugin can still cause problems. Resetting the plugins folder by FTP or PhpMyAdmin.
Rebuild: Re-uploading all files & folders – except the wp-content folder and wp-config.php & root .htaccess files – from a fresh download of WordPress and plugins. Make sure that you delete the old copies of files & folder before uploading the new ones.
