I have a HP Pavilion Dv7 6c90us running Windows 7. My usb modem is the USB551L. I am running Vzaccess manager version 184.108.40.206 (2742g). Everything was working fine till last night when I logged on Vzaccess manager said it's time to check for an update would you like me to check? Answer: yes. It says yes there is an update would you like it installed? Answer: yes. It goes thru the routine installing a new firmware update and software update. And when everything is said and done I get the above message and cannot connect. I have re-downloaded the software directly from verizons website and I have uninstalled the firmware update, the drivers and vzaccess program and reinstalled them (rebooting the computer before reinstallation) and still can't connect via Vzaccess manager. I can however connect directly from the computer bypassing vzaccess manager. After connecting in this way I can start vzaccess manager and it runs fine no problems. Just can't connect directly from VZAccess Manager. I have cantacted customer service and did several things they suggested but still no dice. Still get the "connection failed - a mobile broadband connection profile was not found or is not available". I have gone into the preferences and tried to change the "device connection preference" but it is greyed out and says "LAN adapter manually connect" "auto connect precedence" is also greyed out and won't allow changes. My LAN connection and WiFi connection works fine no problems. It's just VZAccess Manager that won't let me connect.
Normally reinstalling VZAM would resolve this kind of problem. You mention that you already tried this so there must be something else going on.
I wonder if you have access to another computer if you could reproduce this problem or not. It might be worth a shot to borrow a buddies comp for a while to experiment. The modem itself must be OK otherwise it would not allow you to connect from an alternative method.
I suppose a worst case scenario would be re-installing the OS on your computer and starting from a fresh slate. See if you can isolate the problem a little more before you go down that path.
To fix this open VZAM, click options, preferences and change the Device operating mode to LAN Adapter and see if that works