keyboard problem

hy i don't have my macbook for a long time but i already have major problems. few months ago my keyboard went crazy for example when i would try to write an s i would get this ß and it was like that with most of the letters i didn't know what to do so i was trying everything in the end i turned off option key and everything got back to normal until yesterday first it started writing the letter z for no reason when it stopped letters i and k stopped working when i'm tiping on the on screen keyboard i noticed that everytime i press space those weird letters ( ß ) show for a second.
i've tryed to turn on another keyboard and it's working fine. i've seen on many forums that people have keyboard problems but they get almost no answers how to fix them. however i've tryed some things like making a new account or downloading pro efi updater that saved some guys keyboard but my mac doesn't want to instale it. so now i aske you to help me any ideas are welcome

If the Mac works fine with another Keyboard then the fault is in the Keyboard, it needs to be replaced, take it to a Apple Service Centre.

There is nothing you can do if there is a hardware fault, unless you can score a replacement of ebay and take to your laptop with a screwdriver.