are you trying to access wifi while the dongle is connected to a laptop/PC. the wifi is switched OFF if the dongle is connected to usb port of any laptop/PC. the wifi module turns ON only when the device is attached to a pure USB based power source (like charger/battery pack with usb output port)
Here are the steps, that I followed in a computer with Windows 7.
1. Of the two covers in mifi, you'd need to open the second cover (the one that covers the two LEDs). The first cover is for the USB and the second cover is for the LEDs. To open the LEDs cover, you must gently pull that cover from the edges near the two screws.
2. Once LEDs cover is opened, please search for tiny hole near the LEDs. There is also a text "reboot" (in CAPS) near that hole. Just remember it to use it later.
3. Now, use a USB extension cable to connect mifi to your computer.
4. Mifi will probably connect automatically within a minute. Disconnect it now.
5. Close the MTS software (not just minimize it).
6. Use a sharp-but-tiny object to insert into 'reboot' hole-cum-button. Press that button for a few seconds, until both LEDs turn off.
7. Once both LEDs turned off, your mifi is reset with all the default settings.