Js file not opening in browser

Hi All,

I have created an O365 account(trail) for SharePoint and I have added a sample.js file in my assets library.

Till today evening whenever I clicked my JS file, it would open up in brower and I could make changes and edit and add remove code in JS in browser without the need of SharePoint designer.

Now all of a sudden that is not working, now the JS files are not opening in browser which are editable,now they open in browser but they are non-editable and only view only.

I am in an restricted environment and cannot use designer, so have to work in such a fashion.

Thanks in Advance