There are lots of good, free software out there. I use whatever is necessary to clean the system, but generally a combination of Malwarebytes FREE, and either AVG or Avast (I prefer to use Avast) plus CCleaner during the cleanup will do the job. I usually do a few manual checks and deletes and sometimes a safe boot or Live CD boot will be necessary to avoid the processes that block the cleanup tools.
For everyday protection I normally use just Avast and Malwarebytes, plus Adblocker Plus extensions to my browsers. And Malwarebytes is the FREE version, meaning it doesn't stay resident in memory scanning stuff while I'm using the computer. I have to run it when I want to do a check.
IF you can manage to avoid clicking the wrong pop ups, or opening the wrong emails, this should be good. Adblocker speeds up the surfing and does a LOT to keep those dangerous items from coming up to get clicked.
If you post the specific problem we might be able to give you advice on what steps to take to remove it.
MOST IMPORTANTLY: When installing ANY software, be VERY careful to watch for other programs which might be included in the install. For example, a LOT of free, useful, legitimate software comes packaged with other things that you will want to opt out of during the install. Take your time and be sure that what you are clicking on is the correct option.
Worst case scenario, I highly recommend asking a nice computer guy to remote in and help out. Taking your computer to a Geek Squad or similar is the same as putting the install disc in your computer and formatting it. Except they will charge you $100! A trustworthy stranger might charge $40 or so and save your files if it needs to be formatted. Lots of them will do it for free if it's not too much work and they are friends or relatives.