How do I reinstall itunes?

You should make a back up copy of your library to be safe. You can find it in My Documents -> My Music -> iTunes. Copy the iTunes folder/directory to any location with enough available free space.

Next, open your downloads folder and remove all iTunes executables - in fact, nuke everything since these files are space wasters. Then open the Control Panel and depending on your version of Windows, open Add/Remove Programs or Programs and Features. This list takes a while to load, so be patient. When the list loads, scroll down and select iTunes, then click the button to uninstall it.

When iTunes is uninstalled, we need to check the registry since corrupted installs such as yours will often times corrupt the existing key(s). Click the Windows key or Start, then Run and in the text box type regedit.exe and press enter. This will launch the registry editor. Expand HKEY_CURRENT_USER, then expand Software, and scroll down this list and look for anything named Apple, Inc. or Apple Computer, Inc. Right click all of these you find and select Delete to delete the key or keys. Close the registry editor and reboot to be safe.

When your computer has booted back up, go to www.apple.com/itunes to reinstall iTunes. This will install the latest and greatest version. When the install completes, you should find your library intact. Play a few songs, and if all is well you are golden. If you have issues, though, all is not lost. Close iTunes. Go to the location you saved your library copy and right click it and select Copy. Then go to My Documents -> My Music -> iTunes and select the iTunes folder then right click and choose Paste to overwrite the current folder. Re-open iTunes and click a few songs. If they play, you're golden. If they don't, you will need to re-authorize your songs by right clicking them and selecting Authorize for each and every one - there is no short cut for this and I've have to do it a time or two myself. But once the library is reauthorized you are indeed golden.

All the best.

uninstall it then go to itunes then reinstall it

install it again then its automatically reinstall !

no just restart the computer thats all.best thing to do.