I lost Forest set

Sorry still where I can find that forest set modded

What do you mean? The link to download the set is written in my post from Dec. 4th (red marked).

Now it start to be a mystery. Even if I re install Movies in same computer and delete all data files there is still no forest set!??!?

I just noticed that i have it in old studios but when I create new sandbox mode and start from decade 2000, there is no forest set

I installed the game for another computer and the loaded sets never touches that computer and even there the forest set is missing. At least that's for sure the modded sets doesn't effect that.

I loaded the game from internet because i didn't find the expancion pack from any shops. Could that be the reason?

I think the movies just don't fit in the new windowses: 7, 8, 9, 10 etc.

Well, that's really a mystery.
Even if the set is missing in your downloaded version, it should work after you installed the set (mod) I posted.
It's possible that you can't install it on systems that are higher than WinXP but if your PC managed to install it, it should run included the forest set.
So sorry but I really don't know how we could help you.