To preface this issue, I did search the forum (and many Google results) to find an answer to this before posting.
First off, I'm (obviously) new to rooting and in a week of having a rooted Droid, I'm greatly enjoying the experience. I don't recall why exactly I was tinkering with my calendar...it may have had something to do with standing in Disneyland lines all day with the girl and needing something to tinker with. I think there was some kind of Force Close error or something.
The result is, I deleted my calender.apk and calender.odex. I am assuming I am going to have to revert to stock to repair this, and just as well, because I was also foolish enough not to bother backing up with Nandroid or whatever other apps are available for that.
However, before I begin looking into what I need to do to get back to stock (and then root again in a more safe, prepared and calculated fashion), is there any way to replace my calendar app?
I tried downloading a modified calendar.apk from some post I found somewhere else, but the calendar will not sync (Settings->Accounts & Sync->My Gmail Account shows a sync error on the calendar).
Thanks for your assistance. I'll be sure to approach this a little more cautiously next time!