Television cannot get picture after channel 11

Check and replace its tuner.

sadly we have no idea where you live to tell you that .nor what you normally use .here we use 11-1 thru 40-3 for antenna channels .cable ones are found automatically

Back - light problem. Check and replace damaged component/s at its back-light inverter board, or replace this board as card basis. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts. It will be best to replace the inverter board as card basis.
http://electronicshelponline.blogspot.com/
Some model sets; especially LED back-lighted types; the back-light inverter circuit will be part of the main power supply board [SMPS]. In such cases, the power supply board might need replacement.

Try another aerial. ? Just a suggestion.

The TV electronics for the picture may have failed. Do you get any picture ever, like when you turn it on, or when you connect a DVD to it?
If you do then replace the scart cable with a good known brand. Cheap scart cables often do not have all the pins connected up.

Try doing a channel scan or autoprogram of the tuner again. This should fix the issue.

Here is what you need to do to fix this. Call Hitachi Global Storage Technologies & request for the firmware upgrade.
1-800-HITACHI (448-2244)

They will send it to you for free. You get a small SD card that plugs into the back of your TV just below the Cable Card Slot. I wouldn'd have known it was there unless the instructions in the mail packet told me so.

To determine if you need to upgrade go Into the Setup Menu. Then, Go to Software Upgrades & look at the software version. I had 0110.xxxx. the version I upgraded to was 0125.0000 & it fixed the audio problem on 7-1 & 11-1.

now all channels work great.

THANKS HITACHI!!!

You most likely need to go into the menu on the tv and change it to cable mode.

I suspect your tv has gone back to air and should be in cable mode; you will have to go into menu where channel programming takes place. Select cable and autoprogram; it should pick up the missing channels.

Consult owners manual for channel programming. Channel program sequence may be interrupted by weak or drop out of chl 11 signal. This happens occasionally when signal is from standard antenna