Did this used to work before and suddenly stopped working? If so, can you associate it with any software changes, whether an update to Firefox, or to the OS, or to one of your add-ons?

Speaking of add-ons, in case one of your extensions is involved, could you test in Firefox's Safe Mode? That's a standard diagnostic tool to deactivate extensions and some advanced features of Firefox. More info: Diagnose Firefox issues using Troubleshoot Mode.

You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" button > Restart with Add-ons Disabled
• Help menu > Restart with Add-ons Disabled

Not all add-ons are disabled: Flash and other plugins still run

After Firefox shuts down, a small dialog should appear. Click "Start in Safe Mode" (not Refresh).

Any difference?

Pkrys said

If I type a website or search words in the Firefox search bar and hit "return" nothing happens. If it is a website I've been to before, if fills in but when I hit "return" nothing happens. I'm using Firefox 36.0.1 on a Macbook OS X Yosemite 10.10.2

I actually ended up doing a Firefox Refresh. My problem is fixed. Thanks.