HELP EVERYTHING ON MY PC TURNED INTO A LNK FILE!!!?

Guys plz help!! Everything on my PC turned into a LNK file! It all started when I connected my Tablet to my PC cuz I wanted to use the tablet for Paint Tool Sai, so I tried copying WinRar to my Tab and now everything got jacked up I can't open my programs anymore except for Chrome and the icons got replaced by WinRar icons and whenever I try opening a program, It says "The archive is either in unknown format or damaged." I think my programs turned into WinRar files plz help me the computer that I used is not mine!!! I don't want my parents to find out!