always when i update itunes it keeps telling me eeror happen and i cant find the ituunes app anymore!

The general troubleshooting advice when iTunes fails to install properly (and reinstalling or repairing it does not work) is to remove not only iTunes but all related components, reboot, remove the target installation folders and reinstall. For specifics, see the Removing and reinstalling iTunes and other software components section of turfingtest2's guide at:

Troubleshooting issues with iTunes for Windows updates