After manual update, base game no longer launches, will not reinstall. [SOLVED]

Okay, so I've been combing this forum for the past 24 hours trying to figure out what I'm doing wrong/what is going on with my downloads. I'm desperate now so here's what's up:

I downloaded the base game from games4theworld, installed it just fine and have been playing it with no bugs, glitches, crashes, etc. it's been absolutely perfect for the past few days. I then decided to download the Pets and Seasons expansion packs, also from games4theworld. Once they downloaded however, whenever I would try to install them I would get the "This game requires the Sims 3 to be installed blah blah". So I took to the forum to figure out what the deal was, learned that I needed to manually update the game. 

I followed the directions laid out here--I had to do the second point first as it specified because the expansion packs would not install. Once I downloaded and applied the manual patch (which seemed to work fine), the packs still wouldn't install. Then I found that the base game would no longer launch. Not from the hyperlink in my task bar, nor from the program files. I couldn't access the game at all. I even tried to replace the crack into the program file. So I attempted to uninstall and reinstall EVERYTHING from scratch but when I mount the images and try to autorun/install a message pops up saying "Do you want to remove the application and all of its content" followed by a "Do you want to remove your saved content" message. And no matter how many times I do this, or what I try to uninstall, it will not let me reinstall the game.

What in the world am I doing wrong? I'm fairly sure I've already lost all of my content so that's not really an issue at this point--I just want to be able to play the game with the expansion packs.

Thanks for the fast response. I tried to use the revo uninstaller but when i try to uninstall the sims 3 i get this error message:

I can't place any crack file into the EA folder because it no longer exists in my program files. There's nothing there but it also won't let me reinstall the base game. And when i go to my control panel there is a sims 3 in the programs but when i try to uninstall from there i get the same pop up error as above.

UPDATE: I've finally been able to remove every last bit of the Sims from my computer via registry cleanup and deleting data keys and etc and the base game is finally installing. I will update later today on whether or not installation of the expansion packs/ultimate fix works. Thanks so much for your help!

FINAL UPDATE: After working at it most of today, the expansion packs, manual update and ultimate fix all downloaded and the game+packs are working perfectly! It came down to getting rid of everything Sims 3-related so I could reinstall. Thanks for the help!