TV runs fine for a few weeks then will not turn on,leave it unplugged for a week or so then it works again

It sounds like you have a bad soldier joint or dirt behind the button. If you have a row of buttons all of them will be on a rubber pad in the form of carbon buttons. You remove the pad and wash in dish washing soap or shampoo and scrub lightly with a soft toothbrush. Then rinse well and dry with towel and hair dryer, then let air dry for an hour or so. On the circuit board you use rubbing alcohol on a Q-tip and clean the contact points well. You will see little double-S contact points that the carbon buttons short to make the connection. (It's just like a remote control except with a remote you can wash both parts with soap and water.
Look on that circuit board for dull looking soldier joints. They need to be reheated and a little more solder applied carefully.