Hi Gurumoorthy,
Check if any of below options help you.
1. Restart studio pro.
2. right click-> update widget
3. In studio pro go to top menu "App-> Show App directory in explorer->widgets" and check if respective widget .mpk file still exists. you can also manually add it here in case it got deleted by mistake and you have a backup.
Hi Gurumoorthy
You can use HTML snippet for java script