cannot refresh my pc win 8,1

my computer is running sluggish so i want to refresh it in pc settings where it says refresh pc without affecting files but i git a message that says insert media some files are missing when i put in mr win 7 or 8 or 8.1 dvd it says wrong media what can i do to fix this or what do they mean by insert media i got nothing else to put in drive

You can try running sfc /scannow from and elevated command prompt (this will take a while). If errors or inconsistencies are reported, you can run this command: Dism /Online /Cleanup-Image /RestoreHealth

Once completed, you can run sfc /scannow again to make sure the errors or inconsistencies have been corrected and then try your refresh again.

How to Refresh Windows 8 or 8.1
http://www.eightforums.com/tutorials/2293-refresh-windows-8-a.html