Firefox 4.0+ versions have a combined Reload, Stop, & Go button that appears at the right end of the location bar. Only one function is ever active at any one time, so combining them save UI space was a good idea. When a page is loading, it is a "Stop" button, when it finished loading, it turns into a "Reload" button, and when you start to type something into the Location bar it turns into a "Go" button.

To restore the Firefox 3 appearance you can use these steps:

• Open the "View > Toolbars > Customize" window or right-click a vacant area on a Toolbar, except fot the Bookmarks Toolbar.
• Then drag'n'drop the Reload and Stop buttons to their previous position at the left side of the Location bar.

1. Set the order to "Reload - Stop" to get a combined "Reload/Stop" button.
2. Or "Reload - Stop" then put a flexible space in between the two to prevent the buttons from combining.
3. Set the order to "Stop - Reload" to separate them and get two distinct buttons without the space.

there is no stop/reload button in customize I found the reload button, (on the right of the address bar, inside) but there is no stop button

If missing items are in the toolbar palette then drag them back from the Customize window on the toolbar.
If you do not see an item on a toolbar and in the toolbar palette then click the "Restore Default Set" button to restore the default toolbar set up.

• http://kb.mozillazine.org/Toolbar_customization
• https://support.mozilla.org/kb/Back+and+forward+or+other+toolbar+items+are+missing

• http://kb.mozillazine.org/Corrupt_localstore.rdf