can't update itunes

hi, hello. so i went to download the latest software update. i go through it all but it says it can't do it because the itunes update either messed up or wasn't updated. so i check the updates page and it says i have downloaded the latest update for itunes but whenever i open itunes it says i need to update the update that i apparently have already downloaded? so i try to download it again but nothing happens. it just takes me to the updates page, checks for updates and shows me nothing besides the software update. so basically i can't download an update and have no idea how to fix this issue.