How do you get your microsoft windows vista services to set to default?

Ok so my computer is really messed up and i wanted to do a scan. I couldn't find any scans to do so i was thinking abut calling office depot to fix my computer. I went to office deopt's website to get there number. Oh and the reason i was gonna call office depot is cause thats where i bought my laptop and they fixed my computer before. So they had this free PC Scan so i did the scan and it said that i need to set Microsoft Windows Services back to there default values... What does that mean? and how do i do that??? thank you :)