I have tried to package and unpackage a lot of mine with Clean Installer in order to fix it, but after I save the .package file to a .sims2pack file, it will not show this new .sims2pack file. I have looked at the guide for the program, but it seems to show that I should be able to see these files, and I need to access this file in order to fix a lot that causes the game to crash. Does anyone know why this program won't open the .sims2pack file?

How did you save a .package to a .sims2pack?

Sims2pack files consist of package files (and house files). The Clean Installer is for unpacking sims2pack files into your Downloads folder. Trying to change the file type will just bork the file.Opening the Sims2pack file in CI will let you see the CC included in the house.

I don't quite understand what you're trying to do. If the lot causes a crash, it's most likely a CC problem.

I already tried removing CC, and it didn't work. When I open CI, it will show .package files but will not show .sims2pack files. I'm trying to package the lot as a .sims2pack file and then re-extract it as a .package file to see if that will fix it. However, when I go to the folder where the .sims2pack file is located, it will not show up, even though the program shows all .package files.

Wait, is the .sims2pack file present when you look for it normally, like in Explorer? Because if so, all you have to do is open that file with Clean Installer. It should show a list of all .package files contained in that .sims2pack and you can extract them. Searching for the file with Clean Installer won't do anything.

After packaging your lot to file you will find the Sims2pack under Packaged Lots which is a folder inside your Sims 2 folder. Click to open it, remove anything that should not be there and then do save as with a new name. Once that is done if the lot is large or for sharing right click the new clean file and do 'add to archive' to rar it. This makes a smaller file size for uploading.

AFAIK, Clean Installer doesn't show sims2pack files, but should associate the sims2pack extension with itself. Finding a sims2pack in Explorer and double-clicking should open it in CI. If that doesn't work, right-click and Open With should let you open it.

That worked, and I tried to install the file to the desktop. It seemed to work, but the package file didn't show up.

The CI opens sims2pack files, almost like an unzipping program, and installs the packed ".package" files to their proper place.

Do you have the Ultimate Collection? In that case, you'll probably have to fix the file paths to make Clean Installer install files in Downloads.
If you don't have the UC, I think Downloads is the default path. Sometimes it's the SavedSims folder, and sometimes you have to set the path manually.

House files will first show in the Teleport folder, and will usually install properly the text time you go ingame.
Sim files (they have file names with 8x8 digits, something like "5fe278b7_b81ee3dc") should install to the same place the CC files they're packed with end up.