First try moving your antenna around (see the sites listed below for the direction to point the antenna to get a signal). If the antenna has an amplifier, try unplugging that unit. (When an amplifier fails, no signal gets transmitted.) Similarly if you have several TVs sharing one antenna, remove the splitter and directly connect the antenna to this Toshiba to make sure that it isn't causing the problem.
You may be in an area where an iindoor antenna may not work for you. Tall buildings and trees can scatter the signal to the point where a digital tuner can't get enough signal to "read" the data. Again use the results from the sites listed below to check what stations are likely to be received in your area.
Different TVs have different tuner sensitivities. An amplifier may help bring in enough signal to get the channels. (Signal loss is inevitable. However, if the signal is sufficiently poor, an amplifier may give you more noise and won't help.)
There are two sources for a site specific list of channels: Antennaweb.org
. Antennaweb assumes an external antenna and is very conservative in the list of channel that you should receive. (It lists two channels from one transmitter in my area.) Tvfool will indicate the channels that you should get with different antennas (indoor, outdoor, amplified signals).
A rare issue can be that the tuner in the TV has failed. The only way to check that is trying the TV with different antennas (or in different areas - one with high signal strength).
I hope this helps.
(ATSC (digital OTA signals) are either enough to read or not. You can't get the fuzzy signal of an edge of range analog signal.)