Restore to earlier date

I seem to have mistakenly deleted something on my PowerBook a couple of days ago when I was deleting some images and dropped them onto the desk top instead of the bin by mistake. The upshot is that I can't activate Entorage, Word or any of the MS suite and my pics on iPhoto won't open properly amongst other things, although most of the iLife suite works fine! Is it possible to restore the system (like Windows) to an earlier time - i.e. before the problem occurred or is this the only useful function that PCs have over Macs?