Seems remote does not work. to what is the extent of repair?

There is some problem with its audio output section circuit. It is difficult to predict. Your set needs a through check up. Contact any experienced service technician. It will be the best. This is not a user repairable fault. If you wish to get some details; check the site linked here. Pull up older posts. https://electronicshelponline.blogspot.com/ , faults & possible causes to LCD screen are given with illustrations. You can get an idea about the fault to an extent.
Screen-shots to defective LCD and Plasma panels are given. You can see and compare to that to your TVs', and can make sure about the fault to an extent.

If you wish to get some details; check the site linked here. Pull up older posts. http://electronicshelponline.blogspot.com/ Faults & possible causes to LCD & Plasma screen are given with illustrations. You can get an idea about the fault to an extent. Faults to all LCD & Plasma screen are similar, irrespective of its brand and screen size.

If you wish to get some details; check the site linked here. Pull up older posts. Surf the site with patience. http://electronicshelponline.blogspot.com/
http://electro-medical.blogspot.com/
Line, faults & possible causes to LCD screen are given with illustrations. You can get an idea about the fault to an extent.

Remote controls can be repaired to an extent. If you wish to get more details about how to check and repair a remote control, check the site linked here. http://electronicshelponline.blogspot.com/
Pull up previous posts by its left sidebar, or type in the brand name and model number to of your set, to its search box, and press 'Enter' or view it in Mosaic / Timeslide option.

Make sure you assigned your devices to the Extender. This can be done by the following steps:

1) Go to "Device" tab
2) Beside the "Add device" there should be an "Assign devices to..." or something to that extent
3) Select which devices to be controlled by extender!
4) Update extender and remote - make sure you do the extender first!

It will work, to some extent, with most toshiba tvs. You will find that on differant models, some buttons won't work and others won't do as they say but other functions, but will work 100% for same model.

There is usually a remote module mounted on the inside of the front of the tv that senses the remote signal. This controls all functions of the tv. If you are not comfortable in troubleshooting this, I would recommend a repair center.

Try my instructable on how to repair remotes. http://www.instructables.com/id/Repair-your-remote-controls/

does the remote/extention speaker work?
if yes , your internal speaker is faulty > replace it
If no , the external speaker socket is faulty > replace it

Most monitor cables have only 14 of the pins connected, but if you get a fully wired svga extention cable it does work fine.

Steve