Try switching your box off at the plug and checking that the dish connections at the rear of the box are still secure. If it's no different after switching on again, it would appear that there's a problem with your dish setup.
Sky no longer send engineers for Sky+ subscribers unless you have Sky Protect, so you would need to get a local satellite installer to take a look at it. Or now might be the time to consider upgrading to Sky Q - the engineer will sort out any dish issues at no additional cost, when they install Sky Q for you
