If the home button works but you get an unexpected page at startup, there are a couple possible ways that could be happening. Could you check the following:

(1) Firefox desktop shortcut

Right-click the shortcut, choose Properties, and the Shortcut tab. The "Target" should be the following, no more, no less (for 64-bit Windows):

"C:\Program Files (x86)\Mozilla Firefox\firefox.exe"

If you find anything after that, remove it.

(2) Unwanted add-on

Bad extensions often are installed externally to Firefox. I suggest starting here:

Open the Windows Control Panel, Uninstall a Program. Click the "Installed on" column heading to group the infections, I mean, additions, by date. This can help in smoking out undisclosed bundle items that snuck in with some software you agreed to install. Take out as much trash as possible here.

Then, in Firefox, open the Add-ons page using either:

• Ctrl+Shift+a
• "3-bar" menu button (or Tools menu) > Add-ons

In the left column, click Extensions. Then, if in doubt, disable (or Remove, if possible) unrecognized and unwanted extensions.

Often a link will appear above at least one disabled extension to restart Firefox. You can complete your work on the tab and click one of the links as the last step.

Finally, you can "mop up" remaining issues with the scanning/cleaning tools listed in our support article: Troubleshoot Firefox issues caused by malware.

Are you able to get control of your startup?

Go to OPTIONS from menu, select 'General', in it, under the label 'Startup' select Show my home page for "When Firrefox starts", and give the url of the website which you want to set as home page in the column "Home Page".