Lightroom: I did save to catalog and I lost my changes; can I restore my changes? I'm using lightroom 3 on mac. Not long ago I did save to catalog (I don't know what it does) and apparently I didn't select all the photos I have changed.

I opened the saved file and I've been asked if I want to close the software and to open it from this catalog. I pressed yes and I saw just the photos I'd selected before I saved the catalog. When I returned things to the last backup (from a week ago), I saw that all the changes I did from the last week were not there, even if I import a folder that I added in this week it comes up with no changes...

Is it possible to me to restore things to the second before i saved the catalog? when all the changed was there?

What does the save to catalog do?

Many thanks
I'm not sure what "save to catalog" does.  In fact I couldn't even find the command anywhere within Lightroom 4. I always import batches of photos directly into LR straight from an SD card. This automatically adds them to the catalog and saves the raw file in a separate directory.

The catalog is just a database which contains all the edits you do to a photo.  Any changes you make while editing in the develop module are saved the instant you make them.  You can also save the changes as XMP data which is written directly to the raw file so if your catalog ever becomes corrupt your edit data is saved.  There is an option to automatically save xmp data or you can do it manually on a photo by photo basis.

If you use Time Machine or another backup system you should be able to go back and restore to any saved point.