Press SERVICES on your remote control.
Input 4, 0, 1 and SELECT to enter the Installer Setup menu.
Navigate to FULL SYSTEM RESET using the arrow buttons or by pressing 8 on your remote control.
When you see this FYI banner, press SELECT to confirm the reset.
A FYI banner will appear. Give your box time to 'housekeep'.
Once it's done, your box will enter standby mode. Leave it for 5 minutes and turn it back on.
Find another Digibox on eBay or Gumtree. A guide to which box you should get by what manufacturer is available here.
Upgrade to Sky+HD, or Q.