Hi there,
Is there anything you have tried to fix this? A channel rescan for instance?
If that hasn’t worked the issue could be:
Your dish has moved a little.
Or
Water has got in the coax at the dish end. (A common fault…)
Or
LNB has failed or is beginning to fail. (LNBs can fail over time, particularly when exposed to extreme weather conditions; indications of a faulty LNB include missing some channels, pixilation, signal drop-out during heavy downpours or even a complete loss of signal…)
How old is your dish? Has the LNB ever been replaced?