You received a call from a supposed Microsoft technician saying that they received a notification, that your computer contained viruses, malware, etc. and that had infected your computer. These attacks caused your computer to run slow and they need to advise you as to how to remove those infections. A man said that they were from PCOptimizers.
He advised you to log onto a website with a remote access service. You did this and a window came up where they wanted you to list a security number that they gave you, into a box in that window. You hung up a phone and logged off without a listed number that was given to you on another line.
That call does not sound like it was legit. Microsoft does not have technical support call people in a whim like that, that I am aware of. Is your computer still having issues?
If anybody calls you like that again, I recommend not talking to them. I recommend you download and run a free Malwarebytes scan. Make sure Malwarebytes is updated before you begin that scan.
You may need to boot your computer into Windows safe mode with networking. Also, please download and install free CCleaner after running Malwarebytes. Use CCleaner for cleaning your PC and registry cleaning.
You may need to run both clean and registry scans more then once.