Got Homepage I didn't want, Please help

Hi, earlier today I tried to get MGS2 Substance for PC, I went to the torrent site ''the Pirate bay'' I downloaded an installer, and ran the installer, it offered me computer programs (of course) I declined to all their offers, but somehow, the adware was installed anyway, I got MyPCBackup, and a search engine called Isearch123, I've dealt with MyPCBackup before, so getting rid of it was a piece of cake, but the search engine is confusing me, I tried using Iobit Uninstaller, it was still there, I tried using the built in uninstall, still there, I tried deleting EVERY file associated with it, still standing, I tried removing it in the add-ons tab of Mozilla Firefox, nothing, I tried changing my homepage to the default homepage, at this point I was pissed off, I tried blocking the site, nothing, I even tried a system restore point ( I create 1 every day just in case) It wouldn't die, I tried a few more things, still nothing, if anyone here has any suggestions, please tell me, I looked up Isearch123 and apparently it's a virus, please help, my Internet Browser is Firefox, my default search engine is also Firefox, and my hatred for this virus is strong. Please help!

Even when deleting the obvious files associated with malware like this, there's a good chance it has more hiding in places like your temp folders. More importantly, it's also probably created some startup entries, so we'll want to check that out. Go to your start menu, type msconfig into the search box, and hit enter. Go to the Services tab and check "Hide all Microsoft services", and disable anything left over that you don't recognize. Then go to the startup tab and disable anything you don't recognize there (usually you can disable anything under the Startup tab without messing up Windows). Restart your computer and see if it's still resetting your homepage etc.

If that didn't help at all, try installing Malwarebytes (download here). Once it's installed and updates its virus definitions go ahead and run a full scan; shouldn't take too long compared to most AV programs. Once it's done, let it delete/quarantine whatever it finds, then restart once it's done.

Thank you, the Malwarebytes did the trick,