Have Lost Formatting/style Of All Pages

[derbytrader]

I started to install the header tags contribution but then decided to tackle this later.

 

Having reversed (or so I thought) all the changes to files I am left with a functioning site except the appearance is lacking the default colours and the menu links on the header are not contained in a coloured bar but are just a line of separate links.

 

What file or files do I nee dto revisit to restore the style to what it was?

 

Thanks in advance.

[derbytrader]

All sorted, I had not restored stylesheet.css