Without knowing what has hijacked the home page, it is difficult to say how to fix it. ZA can be used in conjunction with those tools.

Download HijackThis selfextracting zip version from here. Once downloaded, double click on the file & it will install into it's own, permanent folder.
Start HJT & press the "Do a system scan and save a log file" button. When the scan is finished a window will pop up giving you the option of where to save it. Save it to desktop where it is easy to access. Open the log file and copy the entire contents of the file & paste it into the body of your post. DO NOT FIX ANYTHING YET. Most of what is there is necessary for the running of your system.