I play in Belladonna Clove mostly and I have modified alot of the buildings and placed new buildings and many households in it
I have played it for a really long time and everything was normal but
I just opened the game and the neighborhood was reset as if this is the first time I've opened it and all the households that were in the bin are deleted
please help

Check if the newer files are really gone from the Belladona folder. They should have newer date stamps than your install date, or than the first files in the folder.

If you don't have a backup, and the files really have been reset, and if the folder has not somehow ended up fully intact in the trash file, there probably isn't much you can do - except for learning that frequent backups is a good thing.

To restore a deleted/lost file or folder
Open My Docs and select the hood folder in C:\Users\(your computer name)\Documents\EA Games\The Sims 2\Neighborhoods right-click it, and then select Restore previous versions.
(Or UC if you use that one.)

This may get it back for you.

I did check in the beginning and all the new files are there. my households and lots but they don't show up in my game