My Google Toolbar (on Mac FireFox) went AWOL overnight – the bar was there at the top of the browser window but completely blank, no buttons. I tried the usual right click on the bar and Google Toolbar was ticked. I went to Google and downloaded and installed the Toolbar again, still nothing.
Then tried clicking Tools > Add Ons > Google Toolbar > Preferences and the Preference window was slightly bizarre with a number of buttons duplicated:
A quick Google Search found this page, and this piece of advice:
I removed everything in ~/Library/Application Support/Firefox/Profiles/<profile dir>/GoogleToolbarData
I followed the instructions, restarted Firefox and my Google Toolbar reappeared.
David Eedle 
Please tell us where you find C://~/Library/application Support/Firefox/profile//GoogleToolbarData in the computer to remove it?
Hi Sue
These instructions are for a Mac, I’m guessing you are on windows, I’m not sure where the file would be I’m sorry. Maybe try searching the harddrive for the GoogleToolbarData folder?
David
See this website for other platforms:
http://kb.mozillazine.org/Profile_folder
Hi, I faced the similar problem in windows but don’t know how to recover it in windows. Please let me know how can I fix this problem in windows.
Sorry, I’m on a Mac and don’t know how to fix for Windows.
David