Question: In zsh when I try and press `CTRL-C` nothing happens (it works fine in bash) when I run `bindkey | grep \\^C` I get `"^C" Applications` so something must've happened... how do I bind `^-C` to the default?

Answer: 
In my case, something had changed the zsh interrupt key (*intr*) to Control-G. To fix it:

```
stty intr ^C

```

(`stty sane` did not work.)

More detail:

```
% stty -a | grep intr
    eol2 = <undef>; erase = ^?; intr = ^G; kill = ^U; lnext = ^V;
% # Control-C did not work. So I used Control-Z to stop the ping:
% ping 1.2.3.4
PING 1.2.3.4 (1.2.3.4): 56 data bytes
Request timeout for icmp_seq 0
^CRequest timeout for icmp_seq 1
^CRequest timeout for icmp_seq 2
^Z
zsh: suspended  ping 1.2.3.4
% stty intr ^C
% stty -a | grep intr
    eol2 = <undef>; erase = ^?; intr = ^C; kill = ^U; lnext = ^V;
# Control-C is working again.  Yes!
% ping 1.2.3.4
PING 1.2.3.4 (1.2.3.4): 56 data bytes
Request timeout for icmp_seq 0
^C
--- 1.2.3.4 ping statistics ---
2 packets transmitted, 0 packets received, 100.0% packet loss

```
I just solved this situation by typing in the simple command `ls` after pressing ctrl-c, ctrl-c.

I think I was in some kind of multi-line input mode.