I assume you've tried new batteries.
Do you know you can check that a remote control is working by pointing it at a digital camera/phone? The sensor on digital cameras is sensitive to the IR signal from the remote and you can see it flashing on the screen. It won't tell you whether or not it's working properly but it will show you that it is, or is not, transmitting.
Others may have a different view, but in my experience when remote control buutons start to misbehave, it's time to replace it.
You can buy a generic universal type (which you have to programme to your TV with sometimes iffy results) or go for the more expensive one that's from the TV maker and works just as it should.
Try turning it upside down and giving it a good shake; take the batteries out and give the connectors a wipe; rub the whole case down with a damp, clean cloth - use rubbing alcohol if you have any.
Put it in a buck of water for half a hour that should do the trick.;-) . Joking aside go on to u tube there's a lot of useful info about cleaning remotes .
I'm with Gingejbee here. I reckon that it's time to replace the thing.
When I bought a remote control last year (for a telly that I'd bought for a fiver without one from an auction ages ago and then completely forgotten about) it cost me the princely sum of six quid, including carriage. So getting hold a new one for your set probably isn't going to break the bank!
I solved this after watching a youtube video many years ago. Take out the batteries. Starting with number 1, press and hold down the button for the count of five. Do exactly the same with button number two, repeat with every button. Then put the batteries back in. It worked for me.
Thank you for answers. Was hoping someone would say something like a quick spray with wd40 would sort problem. Trying solutions or sorting new tv remotes will take me longer, but will let you know how I get on.
it's always appreciated if you report back, as it may help others with the same problem. Let us know how you go on. I had success with the help from the youtube video.
Thank you so much for all offers of solutions - can't say I tried all, but found it was much simpler than I had realised to replace tv remote control with exact copy - ebay £4.95 free postage and is working very well. Thank you