El Capitan broke my keyboard

Go to System Preferences > Keyboard > Input Sources > and select US or British. You may have to click the + button in the bottom left of the window to add one of those options.

Does this resolve the issue?

-Max

Here are the things that i tryed to repair the problem:

*change keyboard layout to english, uk english, spanish iso, etc.. still my keyboard write only weird symbols.

*enter to the guest account (cause' it's impossible for me to enter to my original account, cause i can't type my password) and see if i could change the keyboard layout other there. Nothing happened.

*Errase PRAM, nothing happened

*Enter to recovery mode (CMD + R), and reinstall OS, not possible cause i can't enter my log in information

*Turn on the computer with an instalation pendrive, and hold the option key while its turning on. It doesnt allow me to chose anything

*Install El capitan on a pendrive and boot from there by selecting CMD +R, that worked! i could enter my info just like nothing happened to create my account, but after the computer restarted the problem came back

*Then i connected an usb keyboard to the computer and i could type normally in the usb keyboard, but not in my laptop keyboard.

*When start up the computer on verbose mode it looks like something isn't loading

*When i see the log on the recovery mode it also said that cannot find typography.

As far as it looks, it seems to be a faulty keyboard or a faulty firmware thing...

After this, i will never ever try another beta from apple.

I think what's happening for you is that either the MacBook thinks the alt/option key is permanently pressed down, or it actually physically is permanently pressed down.

First rule out the physical:

Examine the physical alt/option keys themselves (there's two of them) and if one of them looks like it is stuck then use some very thin plastic to carefully loosen it from around the edges. The other possibility is that the is some detritus under the key causing it to seem pressed to the electronics so you could try blowing sharply into them.

If not physical then reinstall OS X:

If it's not physical then assume that there's something wrong with the OS X install. Either boot into Recovery Mode and try to use the USB keyboard to enter your password or boot from the OS X on your pendrive with El Capitan on it and use it to run the El Capitan GM installer to install onto the partition with (the installer that you're running has to not be on the partition with the bad OS X) - this won't affect your user environment or apps, etc - it will just replace all of the system files, hopefully fixing the issue.

Let us know how it goes.

I was experiencing very strange behaviour with my keyboard also. When I tried to log into my iMac from time to time the keyboard response was extremely erratic. Today I experienced the exact same effect but this time I was logged into my iMac and trying to use spotlight search. I would enter a word and it took several seconds for each of the characters of the word to appear. When I hit space bar the space would advance at about 10 to 15 spaces. It turns out my trackpad was the problem. The moment I disconnected it from the iMac the keyboard returned to normal use. I usually keep by trackpad close to the keyboard tray. I've since reconnected it but have moved it up and off to the side. So far keyboard acting normally. I know this does not help Macbook Pro/Air users who are experiencing similar problems but there is definitely something wrong with the trackpad setup. Anyway hope this helps you also.