Thank you for confirming.
Since the issue came up suddenly (losing signal) and won't complete the scan process now, that would indicate that the internal tuner card has failed.
This issue could be a manufacturing defect, but is also often caused by a power event (shock/surge, prolonged over/under voltage condition, etc).
This could also be the result of age related wear and tear, as a 2004 model tv, that type of failure wouldn’t be surprising.
There is one step you can take here, both as a possible fix, as well as a diagnostic evaluation
1) Unplug the power cord from the tv
2) Wait at least 1 hour (60+ Minutes)
3) Press and hold the power button (on the set, not the remote) for 60 seconds
4) Keep holding power button while plugging back in, and for another 60 seconds after. When plugging back in, go directly to the wall outlet, bypassing any power strips or surge protectors.
If this reset process does not work, it would unfortunately confirm an internal hardware failure.
This is something that would require repairs to correct; if you're thinking about a do it yourself repair, you'll need to be comfortable and skilled with electronics repairs, which would require dismantling the set (removing the back panel of the tv), changing out boards, etc, though at this point parts are nearly impossible to find for this 11 year old set. Typically the tuner component will be around a $50 part, when they can be found (used).
If you’re considering repair at a local shop, you’ll find a typical repair to be around $200 for diagnostics, parts, and labor.
For a tv of this size/age, replacement would make more sense. That could mean buying a new tv - you can get a brand new LED tv with a fresh warranty of this size in the $300 range, or you could just bypass the internal tuner and hook up an external tuner box instead, for about $35: http://amzn.to/1SJOUgz
Depending how you’d like to proceed here, I can help with finding parts, finding a repair shop, or recommending replacement options. Just let me know.
Best regards, and apologies for the news,