Seems every time theres a Java update ASDM breaks…
A simple fix is to access via Firefox https://(your IP) and run the ASDM through the browser. Once you successfully connect you will have a new shortcut on the desktop for the ASDM, fixed!
If for some reason you don’t have the shortcut, open Control Panel->Java Control Panel and under Temporary Internet Files select View, click ASDM and on the top toolbar there a button to create a shortcut on your desktop.
Note: don’t bother with IE11 as the quantity of hoops you need to jump through to get it to work will just drive you nuts.