The curved arrow on the right hand side of your address bar will reload the page. Is that what you are looking for ?

Depending on what has happened this article may help you

• Navigation buttons like back, home, bookmarks and reload are missing

Start Firefox in Safe Mode to check if one of the extensions ("3-bar" menu button/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem.

• Switch to the DEFAULT theme: "3-bar" menu button/Tools > Add-ons > Appearance
• Do NOT click the "Refresh Firefox" button on the Safe Mode start window

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

You can reload web page(s) and bypass the cache to refresh possibly outdated or corrupted files (leave out Shift for a normal reload).

• Hold down the Shift key and left-click the Reload button
• Press "Ctrl + F5" or press "Ctrl + Shift + R" (Windows,Linux)
• Press "Command + Shift + R" (Mac)