TV has sound and no picture and i cannot change the channels.

Are you by chance on the SAP audio channel instead of the main channel? You should be able to go into the menu and look at the audio settings. If you are on SAP change it back to main. Some stations do not have audio on the SAP channel.

Sounds like a firmware corruption. Contact the authorized service centre for Mitsubishi. If you wish to get some details; check the site linked here. Viewing it in "Mosaic" will make surf easy.
http://electronicshelponline.blogspot.com/

Hello, it sounds like your inverter board is goin out on the set, when you change channels if you notice on almost any TV the screen goes dark and the new channel appears, it sounds like you are not getting enough power out of the inverter board to power up the backlight enough to come on. This is why the sound remains because everything else works fine and the sound is connected to the main board.

switched HDMI plug from HDMI1 to HDMI2 port and that solved the problem

I hv philips 21RF vardaan TV ,there is sound on AV channel. and the picture is blinking. even some menu setting have changed.. i tried using the service menu but cudnt understand anything. 2 new av channels have come.. av2 and front which were not present before. sound is not coming even on the other channels but picture is fine on them. only on the av1 channel it is blinking., the philips technision had solved this prob once by pressing some code by remote and i don't know the system code

Check option code's.

if there's a channel and volume display but no picture,the problem of your tv is ABL..it is a resistor value from 10K ohms up

install your cellphones with tv remote.. download that from www.mobile9.com.. you can use that to remote you TV.. depends on your cellphones..

Pls more info; what do you mean tv on, picture froze? you are watching on tv chanel, do you use cable? I can help you but need more details.