iTunes not connecting to Internet, even though Internet is working

WI when I open iTunes, it works but has no internet connection. Sometimes a tab will come up saying "iTunes has stopped working" and have the option to close program. If you hit store and home, a screen comes up saying "iTunes could not connect to iTunes Store. Make sure your network connection is active and try again." The Internet itself works, but iTunes won't connect. Also when I plug in my iPad, nothing comes up, just trust this computer on my iPad screen and "start and stop mobile device service" on my computer. I always click yes. I have gone to control panel>administrative tools>Apple mobile device service> and hit start, but it says "the Apple Mobile Device Service service on local computer started and then stopped. Some services stop automatically if they are not in use by other services or programs" I have tried that with iTunes open and closed, same result.

Please give advice, have tried everything. Restarted both computer and iPad.