Doraemonkerpal: No problem. As cool as computers are, they can be immensely frustrating sometimes [and you want to wring the neck of whoever coded the invasive stuff.]
So everything is ok, except your browser homepage keeps getting set to one you don't want? I'm assuming you're running some version of MSIE.
What homepage does it keep going to or setting itself as? That can help us find a way to counter this specific piece of scumware.
If you go into Tools-> Internet options->General, what does it say under 'Home page: Address:' before you change it?
Odds are you have some homepage hijacker still on your machine, and I think most of those write to the registry. I am NOT experienced with manually tweaking the registry, and it's not recommended, so if that's it, we're going to try another way to clean that junk out.
First thing: BACK UP/COPY/EXPORT your registry.
Go to Start->Run and type regedit then click OK.
Then on the left pane of the registry editor that popped up, click once on 'My Computer' [or whatever the top level is], go to menu path Registry -> Export Registry, name the file something useful and save it someplace accessible, and make sure Export range has 'All' selected under it.
Once you've done that, we can see if we can fix your registry.
Do you have access to either Fix-It Utilities or Norton System Works? I think both of those have a registry fixer/cleaner. If you do, after backing up your registry, try the reg cleaners.
If not, you can try these freewares:
http://download.com.com/3000-8022-10227352.html?tag=lst-0-2
or
http://download.com.com/3000-2094-10276041.html?tag=lst-0-3
I have never used either of them, and can't vouch for their quality. They both got pretty good ratings/reviews, however. And at this point, almost anything is worth a try
Let me know what page/site is hijacking your browser, and I'll see if I can find something specific to it.