it says that apple application support wont install. Error 2, what do i do?

With the Error 2, let's try a standalone Apple Application Support install. It still might not install, but fingers crossed any error messages will give us a better idea of the underlying cause of the issue.

Download and save a copy of the iTunesSetup.exe (or iTunes64setup.exe) installer file to your hard drive:

http://www.apple.com/itunes/download/

Download and install the free trial version of WinRAR suitable for your PC (there's a 32-bit Windows version and a 64-bit Windows version):

http://www.rarlab.com/download.htm

Right-click the iTunesSetup.exe (or iTunes64Setup.exe), and select "Extract to iTunesSetup" (or "Extract to iTunes64Setup"). WinRAR will expand the contents of the file into a folder called "iTunesSetup" (or "iTunes64Setup").

Go into the folder and doubleclick the AppleApplicationSupport.msi to do a standalone AAS install.

Does it install properly for you? If so, see if iTunes will launch without the error now.

If instead you get an error message during the install, let us know what it says. (Precise text, please.)

HRESULT:0x8007054F

These ones are typically caused by underlying problems on the PC that also often cause Windows Updates to fail to install. If we can fix the Windows Update trouble, we can usually get the iTunes trouble cleaned up en passant.

Go into your Windows update and try to check for new updates. If updates install, stock up on the ones you're behind on, restarting the PC if requested to do so. After the restart, try installing iTunes again. Does it go through this time for you?

If windows updates fail to install, go into your Update History and doubleclick the failures. What alphanumeric codes appear for you? Are they also 8007054F, or some other number? (If they're another number, what number are you getting?)

Many thanks again.

Let's try the fixit from the following Microsoft document:

http://support.microsoft.com/mats/windows_update/

Does that get your Windows Updates installing again? If so, stock up, restart the PC and try another standalone AAS install.