"Support" would require many more facts about the exact scenario.
- "Every[ ]time I try to sign in" ... to what?
- "cannot connect to iTunes"
- Are you trying to connect a device?
- What type of device is it?
- What specific model number?
- What version of iOS is it running?
- What version of iTunes are you using (do not say "the latest")?
- What type of computer?
- What operating system and version number?