To restore missing channels, you will need to retune your digital receiver (set top box or TV).
The instructions below are basic and not related to any specific receiver brand. Menu descriptions and labels may vary depending on your equipment.
Push Menu or Home button on remote control
Select Settings, Setup, Channel, Broadcast or Installation
Select Digital Setup
Auto scan or Auto tune will appear,
Select and Press OK
Generally It can take few minutes for the tuner to re-scan all the frequencies available in your area. The scan will search for all the channel’s tuning data and save it in your Digital TV or receiver memory.
For specific retuning instructions, consult your equipment manual.
In most cases, retuning the TV solves the issue. Otherwise you may have to reset your antenna connection cable and retune again or get a qualified antenna technician to check your antenna system if there are no TV reception issues in the area.