You can start by downloading
Malwarebytes - run it and remove all it finds with a full scan.
1-What operating system are you running?
2- is it 32 bit or 64 bit?
3- Laptop or desktop?
4- Have you tried a system restore back to before the problem?
A little more info would really help us to suggest a solution for you.
There are more great free tools that will work for you.
If you don't know the answers to my questions, here is a simple How-To that will help you:
Some HELP in posting on Computing.net plus free progs and instructions Cheers