Is this what you are talking about? http://livereload.com/

This looks like it uses a plugin to work with the browser. Firefox v52+ disables all plugins except for Flash Why do Java, Silverlight, Adobe Acrobat and other plugins no longer work? {web link}

I am not sure if this applies so I called for more help.

You can install the Firefox ESR 52 version which will get security updates into early 2018, to get "more time" using Firefox.

ESR

Firefox; Extended Support Release {web link} ESR Notes System Requirements

AmelBio said

i need to instal livereload in firefox for sublime text 3 please help if you can.

You appear to be Testing Nightly developmental builds of Firefox 59.0a1. The Nightly channel gets checkins with two updates each day. There may be issues as a result until fixed, finished or reverted. Pretty soon 60.0a1 will be started on Nightly channel and 59.0 will be on Beta as 58.0 is scheduled for Release on Jan 23rd. Release < Beta (b#) < Nightly (a1)

The Nightly channel of Firefox is not the best option if you want applications or Extensions to work.