Tricia, what joy to read - in a good way :), these are the untold happenings that occur to all of us and some time, in short stuff like this happens... and you only learn from the own experience. I had a professional speaker trainer tell me that;
1, get there early - meaning in all your preparation makse sure you both physically get your presentation done early, physically get to the location early - that allowes you to both dry run and "feel" in the location properly, get there early mentally - meaning when you start your presentation it has already run to completion a few times i your head already, this allowes you to improvise should something happen.
2, God is in the details - make sure YOU like what you are to talk/present about and pay attention to the estetics of it all if you use visual aids, if you dont make extra sure that you have the details for the words down properly.
3, Have fun - try to be the energy that you want come across, and if you have fun you are less likely to get stressed yourself from any misshaps - infact, a misshap can quickly be turned around to be an adventure for the audience.

first time I had to rely on these3 steps was when adressing over 300 people at a EU conference, I had 15 minutes to present, and the power went out completely... emergency lighting came on and we were told over speakers that no need for alarm... I ended up using my remaining 8 minutes to present unplugged, a naturel... it was the scareist most fun thing that I ever done - and turned out well recieved.

yours
jonas