Easier then this is to run:
xmodmap -pk | egrep '^[ ]+67 '
and you should see XF86_Switch_VT_1 in the output. If that's not the case then definitely
your key mappings are wrong. This would restore Virtual terminal switching, but may create bigger problems
xmodmap -e 'keycode 67 = F1 XF86_Switch_VT_1'