Toshiba 42HL196 tv won't turn on, red led flashing

Suggest obtain the owner's manual and follow the steps.

check some leak or bulged capacitors at the power supply board then replace it.

Not sure right off bat, however unplug it from the wall for three or four minutes plug it back in it might reset it?

If the tv doesn't reset after being unplugged awhile, there's an internal problem, and the unit will have to be serviced. Make sure the cable input isn't loose, and that the cable cord is good. Aside from that, there's not much you can do. Some cities have mobile TV repairmen that will service the unit in your home, and it's much more convenient. Look in your Yellow Pages under TV Repair.
Good luck, and hope this helps.

SYMPTOM: Won't turn on or intermittently won't turn on, Red LED Flashes.

CAUSE: Loss of Main Switched Power Sources. Standby power is OK.
SOLUTION: Replace Regulator IC Q820 with Toshiba Part # 23135094

Power and OPC LED lights flashes?Common on Sharp LCD tv.Tv is still useable.Tv have Tuner signal board problems.Every times Power and OPC LED lights flashes.Just push the remote power button again and wait.Sometimes Power and OPC LED light will flashes require push power again wait again Power and OPC will flashes two or three time push power button and wait.Must do this two or three time before the backlight will light up and tv work.

toshiba 42hl196 lcd the power led red light flashers totally 3 time on tv on pictuce

Those blinks [flashes] are fault indication (Error Codes). From the number of blinks occur at one time switch ON, you can get an idea about the faulty circuit section inside it. This will make repair easy. These are called blinking codes. Make sure about the exact number of blinking of the standby/power LED, by switching On & OFF the set, for at least two times. Count it carefully. If you wish to get some details, check the site linked here. It has details about blinking codes, and fault locating procedure, to many popular brand TVs and other devices.
http://homenol.blogspot.com/
http://electronicshelponline.blogspot.com/
If blinks continue without any pause, the main board is faulty.
Search the site by type in the "brand name" to your device, in the "Search box at the top right of the display window of the Homepage" to get gathered related posts.

Sorry but you are out of luck, the unit will need repair. It could come back to life in any moment but most often is related to this:

My previous post here

good luck,

mrwindex

The LED used in most tv are dual color led,some have two lead, some have three. try to find the same size and replace it.