So I was trying to install New York City but where I got the file is from .sims3pack which means you have to register an account which means I have to enter the CD code which I do not have, is there a program which can convert it to .world? Because my .world causes problems and if i want to play it, im going to need to restart my computer... Any ideas? Or it is just what it is? I tried to look up the sims 3 .world downloads but it comes up with "The Sims 3 World Adventures (which I do have)"

Yes, you would install it via launcher as any other sims3pack.

If you want to make it a world file in order to avoid the launcher (as I do, too), you will need to unpack it with Delphy's Sims 3 Pack Multi-Extracter here: http://modthesims.info/d/364038
I have to warn you though, this method requires knowledge of package files and how to use s3pe. Also, with worlds that use lots of cc as the one you want to install it's quite tedious, too. Not all items you extract may work as intended (counters for example, some pattern etc.)

You will get a ton of package files with a world like New York CIty because it uses a ton of cc. Now you have to sort through them and find the one that is actually the world. It might be the biggest package file but then, especially in this case, it might not. You will have to go through them and peek into the files with s3pe. You'll recognize the world package because it got a WPID ressource. Change the file extension from .package to .world.

This file goes into the worlds folder of your Base game installation, NOT into your mods folder! The path for Win 7 on a PC with installation from disc is this one: C:\Program Files (x86)\Electronic Arts\The Sims 3\GameData\Shared\NonPackaged\Worlds
I don't know how it looks like if you installed via Origin or are on a mac or any other windows version, sorry. Might be similar, just look for the NonPackaged\Worlds folder.

The rest of the package files go into your mods folder as all package files. This is the cc used.

I meant you need to register an account to install .sims3packs