Codes reappearing after deleting and not working anymore

Okay, there is something dodgy going on on my forum.

I have an image for the background and all of a sudden it's started to repeat itself and doesn't look seamless. How do I get it back to normal? It looked normal yesterday and when I logged on today it was a mess. Pluss in the CSS area there were some codes in there that I had deleted and now they're back. Plus the codes stopped working one day.

What is going on?

Noone else has an acces to the admin panel.

Hello,

So you don't want the background image to repeat, right? Please try adding this code to your CSS...

Code:

body {
background-repeat: no-repeat;
}

Add it at the end of your stylesheet.