Site removed from google for some phrases

But will it be put back...

[Richie]

For a long time now I have used PHP on my site to determine whether it is Google bot that is accessing it. If it is google, no ALT text is displayed on images because it looks really messy on the Results Page Snippet.

I have now noticed that my site has been completely dropped from one of my main and most popular search phrases which used to put me at the top of the results for that phrase. So now one of my competitors is at the top and I'm not even on the results at all.

I do however still have a 3/10 PR for my home page (which is still not great despite all my efforts).

The only thing I can think of for this is the Alt text thing. I did it a while ago but now realise it might actually be better to show alt text to google as well as users, so I have removed all of that PHP coding.

But will Google soon notice I have made that change, and put me back in the results for my popular phrases?