My Toshiba Smart TV is only 2 years old and keeps switching channels on its own.

Your EEPROM has some bad files on it. It's an expensive IC to chance if you have the equipment and knowledge to replace it, other option is replace the main board

I have a 55inch thorn TV not a smart TV Tho n it keeps randomly turning off day and night n once it flicked from hdmi channel to normal TV channel, no set some or anything I'm worried a fault or boogidy, it's bout 5 or 6 years old n only been doing it the last week ??

Did you try changing the source? It might be getting the channel from a source other than the TV.

Will you check the channel button at the side of your television if the button will normaly press on.If not,the problem is in the system of your TV.Ethier the system ic is deffective.Its better to repair the authorized technician.

Digital tv channels use analog carrier frequency of old system then changes to digital tv numbers later in the tuner memory. Leave tv on or standby at all times to have tuner set the digital tv numbers in its memory. You can reset the memory by pull the plug on the wall for 5 minutes then reconnect to the wall plug.

Sounds like somehow the TV got switched from Cable to Antenna.

If there is a Menu look for a way to switch it back.

If it is REALLY old there may be a Cable/Antenna toggle switch on the back of the TV. If so, put it in the Cable position.

This is a very common problem in these sets. I would recommend taking it to a certified repair shop. What normally happens is that the x-ray protect transistor starts to "leak" (electricity, not fluids) and shuts the unit down. The repair is not too costly.

The problem has cleared itself a day later after being switched on/off a few times.I suspect the 'computer part' of the TV (channel processor, instruction decoder etc) received maybe a power glitch or an illegal infrared instruction (2 remotes used at once for example) and 'locked up' leaving just the analogue side operating.
I was going to continue happily using it with just the analogue side slaved to my Hd recorder for digital signals but it seems to have got over whatever it was that upset it.

http://home.earthlink.net/~oleg.filippov/ConvergenceFix.htm
http://cmpalmer.blogspot.com/2006/11/fixing-my-own-tv-part-ii.html