PLEASE HELP! Web site has stopped working!

I have three wordpress websites and I use this theme for all of them. I started off with no knowledge at all but through research, I have managed to do some nice things with my websites without bothering anyone for any help. I have now made a big mistake.

I have first added a link to one of my websites, on the footer of another in ATO>FOOTER>FOOTER CONTENT which looked like this
this work without any problems so i tried to add the same link on the second site. The link was added with a whole load of jargon at the end so I had to remove it.
I went into functions.php and added the code where I had previously taken out the 'by wordpress' bit.
I then got a page error. I went back a page and tried to put the code back to what it was (conferring with my other sites php) but every time I save i get page errors.
The site is no longer active and need some urgent help to rectify my silly mistake!
I have the option to upgrade to wordpress 3.4.1 but im not sure if that would wipe away my worrys?
My site is www.premiersuiteandlounge.com
Thank you for any help!