Try doing a "File Save-as" but keep the same location and give it a new file name by simply adding a '1' or some other character to it. Hopefully the new file will not be read-only. Delete the existing file and you can then 'rename' the new file to be the same as the old one by removing the extra character.
What is Markdown?
Markdown lets you add more formatting to your post. Simply type in your post and it will display as written.
If you wish to add bold or italic characters, add a hyperlink to another website, a heading or a horizontal line, simply use the relevent icons above the text input field.
A preview of your post will appear in the grey box below. If you make a change and you're not happy, simply press the back arrow icon to undo.