Computer help please

So basically, something Is up with my laptop and it is getting really frustrating.

Can you guys reccomend security programs/stuff that will scan my computer and keep it running okay? Free please, anything that works for you guys to clear things up on the computer. I don't have the money for good securuty programs.

Also, would anyone be able to help with a folder issue? I'm unable to make new folders on my laptop and have no idea why when it used to work fine. I googled it but a huge thing of words/code popped that was literally like an alien language.