I often get asked the question, “how can I clean up my computer?” I must first say this, if you’ve been infected with a virus or spyware, there is no guarantee that anything short of a complete system wipe will completely clean your system. Please read this post for further explanation.

With that in mind, here’s a good system to use in order to try and clean your computer (this is for a Windows PC).

I recommend superantispyware, malwarebytes, and avg free. They are all free to use. Some of them have paid options that give you more configurations and automatic updates. Are you using any anti-virus software now? If so, is it up to date? If not, you need to start by installing avg free right away.

http://www.download.com/AVG-Anti-Virus-Free-Edition/3000-2239_4-10320142.html?part=dl-AVGAntiVir&subj=dl&tag=button

(be aware that it will also try to install a security toolbar, uncheck that because it’s not necessary)
After that is installed, make sure it downloads the latest update and do a complete system scan.

Next, download and install superantispyware.

http://www.superantispyware.com/download.html

Again, make sure it updates and run a complete system scan. Reboot your computer when it’s done. If it found anything the first time, run it again. Keep running it again until you get a clean system scan and reboot the computer between each scan.

You can now uninstall superantispyware.

Next, download and install malwarebytes.

http://www.download.com/Malwarebytes-Anti-Malware/3000-8022_4-10804572.html?part=dl-10804572&subj=dl&tag=button

Do the same thing that you did with superantispyware, update it and keep scanning until you get a clean scan.

You can uninstall malwarebytes once you’re done. You definitely don’t want all of them running at the same time. Do them one at a time. Also, if you keep any of them installed, keep the AVG and uninstall the other two.

If at any step so far, you are unable to get a clean system scan after trying a few times, your system is not going to be cleaned without a complete hard drive wipe. This means it’s time to backup all your valuable files (be careful not to backup any of the bad stuff), format the hard drive and reinstall everything from scratch.
If every thing so far went smoothly and your system scans are clean, download CCleaner as a final step.

http://www.filehippo.com/download_ccleaner/

This is a great program that cleans up your system. Run it weekly or every other week. It doesn’t clean viruses, it cleans crap (it was originally called Crap Cleaner).