My control key doesn't work, how do I fix it?

"You probably need to fix your modifier mappings.

Do a

xmodmap -pke > my.xmodmap

Use xev to check the scancodes of your control keys, and make sure they're set correctly in that file.

e.g. for me:

...
keycode 37 = Control_L NoSymbol Control_L NoSymbol Control_L
...
keycode 117 = Control_R NoSymbol Control_R NoSymbol Control_R
...

At the end of this file, add:

clear Control
add Control = Control_L Control_R

(btw, you can see your modifiers by running 'xmodmap' with no arguments.)

Then feed-back the modified mapping file:

xmodmap my.xmodmap"

Hit 'layout options' in the screenshot you posted. Is anything bold? is there anything checked for right control under of the settings?

"I have not Right CTRL on my keyboard, but instead of it i have Insert key.
I run xev and press Insert. I see that Insert generate keycode 106.

Now, to map my Insert key (keycode 106) to Right CTRL i do something like below and works (for example Ctrl+T in Google Chrome). Maybe that will help You.

xmodmap -e 'keycode 106 = Control_R' -e 'clear Control' -e 'add Control = Control_L Control_R'

I put this lines into my ~/.xinitrc and ~/.xsession to setup remapping on X startup."

"I had same problem with Ctrl not working in Firefox. Here's what fixed it for me:
Go to Compiz->General->General Options->Key bindings. If any combinations include Ctrl, change to something else, such as Shift."