Antivirus free?

Avast is one of the best free anti-virus program.

Try CCleaner and AdwCleaner if you think you got adware.

Sounds to me like OP's browser was hijacked. Malwarebytes should be his first step. Then once his data is secure on a remote drive, he should reinstall his OS.

Running without Antivirus is not wise. Average infection time without AV is less than 1 minute.