Firefox Plug-ins not working

Hi ya'll!

I hope I have this on the right board.

I used to have the Firefox SEO plug-in on my computer. Recently, I had my computer worked on by the Geek Squad and when I got it back, the plug-in was gone, so I re-installed it but I don't see it on my computer when I look at websites. I checked the plug-in instructions and everything is checked like it should be. I actually see the SEO icon on my toolbar but when I click it, nothing happens.

I loaded another Firefox plug-in to help with code on websites (can't remember the name of it) but it's not visible either, too. Could the geeks have done something to my computer settings so that plug-ins wouldn't work? I hate to be so accusatory but don't know whatever else it could be.

By the way, I am using Windows Vista.

Thanks for any help!