How do I fix my Dual 26" lcdtv model DLCD2605 on/off switch?

Hi, If anyone can help I would really apprecite. I bought the above tv around xmas last year and everythingwas fine until two days ago the on/off switch started m,aking a funny buzzing noise and ojly worked now and again. Tried to take it back to Argos, but cant find the receipt AND I paid cash. Long story short they wont have back or repair unless I can remember the exact day I bought it and the catalogue number (they dont stock anymore tho) head and brick wall come to mind. Back to my problem. would i be able to order a new switch and swap it myself????