Missing Files from Windows 8 Pro + Media Center

I have stupidly removed some files from my Windows 8 Pro + Media Center it works but only just, Its on a DELL Latitude10  Tablet, My problem is I have no idea which files I have removed, can anyone help me to find the missing files so I can restore my Tablet to a full working Windows 8 Pro. I am no Geek, I,m 72 but not yet lost all of the grey matter. As this is my fault you may disagree with that,

Thanks