To restore your menu bar, tap the Alt key or press F10. Then use

View > Toolbars > Menu Bar

That will switch you from the orange Firefox button back to the classic menus.

As for right-click, I don't know why that wouldn't be working.

Also, the browser you posted here with says Firefox 3.5.5, not 4.0. See this:
https://support.mozilla.com/en-US/kb/websites+or+add-ons+incorrectly+report+incompatible+browser

You can find the Copy, Paste, and Cut buttons in the Edit menu and the Edit sub menu in the orange Firefox menu.
You can also find them as toolbar buttons in the toolbar palette in the Customize window and drag them on a toolbar.

Open the Customize window via "View > Toolbars > Customize" or via "Firefox > Options > Toolbar Layout"

• http://kb.mozillazine.org/Toolbar_customization

For your right click issue:

Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of the extensions is causing the problem (switch to the DEFAULT theme: Firefox (Tools) > Add-ons > Appearance/Themes).

• Don't make any changes on the Safe mode start window.
• https://support.mozilla.com/kb/Safe+Mode

If it does work in Safe-mode then disable all extensions and then try to find which is causing it by enabling one at a time until the problem reappears.

• Use "Disable all add-ons" on the Safe mode start window to disable all extensions.
• Close and restart Firefox after each change via "File > Exit" (Mac: "Firefox > Quit"; Linux: "File > Quit")

See also:

• Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems