My messanger stopped working, will not allow me to sign on due to error message Internet is not working?

I have input my Yahoo ID, valid Pword but the messenger does not activate. I have downloader version 9 a second time but still cannot connect. I can access all other parts of Yahoo, and other internet web sites so I am pretty sure it is a messenger problem. Is there any one out there to help get messenger working again. Suggestions of things to check etc. Thanks Dennis newman.d@comcast.net.. dnewman350@Yahoo.com