Cant install itunes again

Question

PLease help me, im start with problems after a pop window ask me to upgrade itunes, i accept and then the error 2356 saying that last version of itunes cant be uninstalled, the installation finishes and now itunes dont open.
I tried a lot of things, removing from add or remove programs, windows install clean up, deleting the itunes and quicktime folders, even deleting from registry but all fail.
Help me somebody please, i need to install itunes again

Answer 1

So what exactly did you delete from the registry. I sure hope you were VERY careful. The MS cleanup should work just fine but to make a very clean pc you need to do a few extra steps.
Redownload a QT standalone installer.
Redownload a itunes install w/out QT.
Uninstall any itunes or QT from add/remove or use the MS cleanup.
Go to C:\WINDOWS\Downloaded Installations. You should see folders like {06EB3288-C5F4-4C73-8EEE-AC798668FF66}
Look in each of these folders for itunes.msi and delete the folder. Be careful to ONLY delete the folders containing itunes.msi
Clean out your temp folders, Delete as much as you can in these folders except for the folders Cookies, History, Temporary Internet Files.
a. C:\windows\temp (if one exists)
b. C:\Documents and Settings\{username}\Local settings\Temp
Sometimes installers will pick up old files or won’t delete their temporary files.
I didn't see which MS os you are using, so I assume you are using XP.
Go to http://www.download.com/3000-2094-881470.html and download the regcleaner. Unpack it and run it. This is a nice utility that will delete broken registry entries and create a file with them. This way if it deletes anything needed you can add it back. Note I never had to do this with using it for many years. Also it doesn't list XP as being support but you'll be fine.
Reboot your PC.
Make sure you don't have a c:\program files\itunes and QT folders here.
At this point you should be able to reinstall QT and itunes. I would suggest you rebooting the PC between each installation. Also be sure to turn off not just disable, as many system services that are running. These are the little icons by your clock. Report if you are still having trouble installing or have additional questions.