There are several free anti-virus programs which you can use now. See Choosing an Anti-Virus Program
I recommend you choose and install one ASAP, then perform a full scan.
Then download and use the following tools (in the order listed) which will search for and remove many potentially unwanted programs (PUPs), adware, toolbars, browser hijackers, extensions, add-ons and other junkware as well as related registry entries (values, keys) and remnants.
1. Download and run RKill
created by Grinler
(aka Lawrence Abrams
), the site owner of BleepingComputer.Important: Do not reboot your computer until you complete the next step.
2. Download and scan with AdwCleaner
created by Xplode
-- Note: The contents of the AdwCleaner log file may be confusing. Unless you see a program name that you recognize and know should not be removed, don't worry about it. If you see an entry you want to keep, return to AdwCleaner before cleaning...all detected items will be listed (and checked) in each tab. Click on each one and uncheck any items you want to keep (except you cannot uncheck Chrome and Firefox preferences lines).
3. Download and scan with Junkware Removal Tool
created by thisisu
after allowing AdwCleaner to restart the computer.
4. Download and scan with Malwarebytes Anti-Malware