I don't think it has to be saved anywhere.

When you create a new profile, is there any such file associated with this ?

It's in a compiled code, why are you asking about it? What do you want to achieve?

If some of those menu options have disappeared is there a way to get them back ?

Hi, I'd say that's most likely a bug. What options have disappeared? Does the issue persist in Troubleshoot Mode?

The issue does persist in Troubleshooting mode.

Then please report this on Bugzilla, Mozilla's bug tracker, so that the developers can take a look. You can also share a link to your bug report here.