Sounds like this problem:
http://answers.ea.com/t5/The-Sims-4/INFO-REQUEST-Houses-Lots-disappear/m-p/4620279#U4620279
The thing is I accidentally saved the game already and I tried deleting some saved files but nothing is working... I don't think that will work considering the fact that I have already saved with my house disappeared.. and when I click on the lot, nothing pops up. It won't let me play any of the other sims on the lot and no option to even bulldoze or go into build mode... I've moved my sims into a new household but I really preferred my old home. Thank you for your reply though!
Willing to share your save game ?
If so, please zip up this folder: documents\electronicarts\thesims4\saves and drop the file to this Mediafire-Link to upload.
Please make sure to name the zip file with your user name.
Community Manager
