Hi try turning it off and on again. Sometimes when power is restored it will search for updates and an install update screen appears. The update is broadcast at certain times. I dont know what model you have but the broadcast times are listed here:
http://www.dtg.org.uk/industry/download_schedule.php
When my remote froze and I turned the box off and on the remote worked for a while (about 2 mins) if this is the case then you can use the menu to find the update software screen I have a PVR 9150T. but I am sure it will be similar to other models. The user manual will explain further.
Using the remote go to: menu – installation – software update – automatic update
But remember that the update will only be available when stated in the download schedule above:
You can also use a computer to install the update but I have never done this so someone else will have to help you if the above method does not work. Again it will explain in the user manual how to do it.
I am no expert but this worked for me
Hope this helps
Paul M