reboot your pc.
on the startup loading screen, hit f11, run safe mode.
in safe mode, download spybot search and destroy, ad aware, hijack this, and malware bytes anti-malware. these are all free programs and it should get the job done. also if you're running firefox get ad-block plus, also free. it's an addon that disables all ads (even youtube ads), and gets rid of smelly pop ups.
if all is lost system restore back a week or so like theodore said.