Hey friend. Try "Data Enabler" from the market by FARPROC. Make sure that you use the one mentioned on the left as there is at least one other similar tool that is named identically, but doesn't work nearly as well. It is the best I've found at cycling the 3G and 4G radios and getting either one to connect to the Google servers and give you back the connectivity. It works for me even when the Airplane mode cycling doesn't work. It's an app but works as a widget, or in other words...you install it and then you create the widget on the home screen to activate it. Trying to activate it by running the app from your app tray or if dropped onto the home screen will only pull up a notice page that tells you to add the widged.
I find my phone in a "White state" with either 4G or 3G, so I tap the widget, the green light goes out, the 4G or 3G icon disappears. Then I tap the widget again, and like clockwork, the 3G or 4G icon reappears, and with in seconds the "White state" reverts to the connected "Blue state".