i could not download from itunes error (-50)

Restarted the computer?

iTunes Store: Error (-50) when downloading purchased content - http://support.apple.com/kb/TS1583

Advanced steps for fixing issues with iTunes Store connection (formerly: "iTunes: Advanced iTunes Store troubleshooting") - http://support.apple.com/HT203361 - document used to include a long list of iTunes error codes, some of which are here: https://support.apple.com/HT203174