Symbols appear instead of letters/numbers when typing on Mac Im using a Mac book air and when I try to type something, random weird symbols appear instead of texts. The symbols "Œ„´‰ˇÁ¨ˆØ∏" appear when I try to type "qwertyuiop".

I had already found a solution although it is only temporary. 

I revert my keyboard through following these steps: 


Open system preferences
Select accessibility
Select keyboard
Enable sticky keys
turn it off 
Problem solved!


However, every time I close my laptop it makes the same error again and I have to fix the accessibility settings each time. Although everything else is working fine I'm still looking for a long-term solution to this problem. I wouldn't want to go through the hassle of logging into the guest account just to change the settings in order to be able to type the password in my main user account on my mac.
Your qwertyuiop result indicates that your machine thinks that both option and shift are being held down while you type.  The symbols are not random but exactly what is supposed to happen when those keys are depressed.  Normally this would indicate a damaged keyboard, especially if you try another one and it works ok.