I'v not formatted my pc since last 2 years, consequently my computer has loaded up with a:
lot of unused files in C drive,
a lot of DLL files,
and a lot of folders
Please suggest me any method or software to get rid of these stuff.
How do you know the .dll's are unused? Uninstallers delete those when the programs are uninstalled. Some .dll's are used for multiple programs. You can try CCleaner. I've used it to keep my PC's fresh and sweet smelling.