Q: unable to install the new itunes and the old one is gone now. get error message that reads "starting service failed to start? now what?

Try restarting your computer. Download iTunes and before installing it, temporarily disable the firewall and antivirus.

Take a look at this article, maybe it will help you:

How to restart the Apple Mobile Device Service (AMDS) on Windows - Apple Support

Hope this helps!

For general advice see Troubleshooting issues with iTunes for Windows updates.

The steps in the second box are a guide to removing everything related to iTunes and then rebuilding it which is often a good starting point unless the symptoms indicate a more specific approach. Review the other boxes and the list of support documents further down the page in case one of them applies.

The further information area has direct links to the current and recent builds in case you have problems downloading, need to revert to an older version or want to try the iTunes for Windows (64-bit - for older video cards) release as a workaround for installation or performance issues, or compatibility with QuickTime or third party software.

Your library should be unaffected by these steps but there are also links to backup and recovery advice should it be needed.

tt2