Was playing last night when I had something happen I've only heard of happening to others.
My sim was at his community lot, running his party shop and had just achieved a rating of 9 for his business. Everything seemed to be going smoothly until my game suddenly crashed. I'd been playing the lot for 4 hours, and had saved the lot periodically, not realizing this was not a good thing (saving the community lot with my sim on it). When I rebooted the game and went back to my sims home lot, it would not let me enter it, and and stated that my sim was on a community lot and asked if I want to go there. I clicked okay, and after the lot loaded, I was in the build/buy mode on the lot, with no option to play. My sim was there, but I could do nothing with him, nor play the lot. I exited the lot, went to another sims lot, and said stuck sim was one of the visitors my next sim recieved when the welcome wagon came. So I played the lot for awhile. When he left, I saved the lot I was on, and went back to the home screen and the stuck sims lot is still not enterable. So I went back to the community lot and he is still there, and there is still no play mode for the lot.
I have all ep's (except for BV, Pets, FT and M&G). I have all patches installed. I have searched the wiki for answers, but most say this is something that should have been fixed with the OFB patch, which I have installed. Is there something I can do to get this sim back? Or is the whole neighborhood borked?

Try this:
http://www.modthesims.info/showthread.php?t=456244

Thanks, Mootilda! I'll give these all a try tonight when I get home.

Mootilda, thank you!!!
I printed the link you gave me, and followed the instructions and had no luck with the magic wand, CJ's lot unsticker, or the batbox. So, I backed up my game, and opened SimPE, and followed your instructions. Worked like a charm!!!
Since my lot only had build/buy mode, I could not use the items mentioned above, as the lot was unplayable (the button for play mode was greyed out). Not having any experience with SimPE, I was nervous I'd do something wrong, but your instructions were so easy and painless to follow.
I am putting these instructions in my file for emergencies, as they were the cure for whatever went wonky with my game. Again, a great big thank you!!!

I'm glad that I could help. I know that a lot of people are nervous about SimPE, which is why I suggest the other options first.