bonjour

A simple question that could hide a multitude of issues.
You need to give you operating system and a full description of the problem you are trying to solve with any error messages in full.

Simple answer:
You need to be an administrator. Type services in the search box and click on services in the program section.
Find the bonjour service,right click and select start.

The simplest answer would be to Uninstall and then re-install iTunes. That will remove and re-add the Bonjour service/files.

I am afraid that is not true, uninstalling iTunes does not uninstall Bonjour. If you want to uninstall Bonjour you have specifically uninstall it.
http://support.apple.com/kb/HT1923

Yea, that was my bad. When I think of uninstalling iTunes, I usually uninstall everything that came with it (Apple Application Support, Bonjour, Apple Software Update, Apple Mobile Device Support, Quicktime, and iTunes).

polydorus wrote:

*You need to be an administrator. Type services in the search box*

Please - which search box and where is it ?

Message was edited by: Dan Mitchell1