It needs to find the associated server code before it will appear in server behaviors. It does that with a pattern match, so the jibberish you added prevents it from finding the pattern it is looking for.
Really unless you are adept at writing php and debugging, you shouldn't be editing in the code. You should be using the server behavior window. If you use that interface for edits, it will recognize them when they are applied.
Do you have a backup? If not, remove your jibberish and the server behavior should reappear. Then go to design view. Double click on the add to cart server behavior and use the bindings window to set the values of those columns to come from the recordset.
You basically have to continue hand coding once you start, so if you aren't prepared to debug your updates you should avoid making changes by hand in the code.