my existing outlet for my AC is 240V now we bought a new unit w/c is
110V, but when i opened my 240V receptacle it ony has 3 wires, 2 hot
wires w/c is both 110V & 1 ground, no neutral wire, my question
is:


line & its now working as 110V, how dangerous is this?

Extremely. Kill the breaker ... now!

2. i have no neutral wire, what is my other option to make my outlet a
110V w/o using the ground as the other line

You say you have 3 wires. Open your panel, replace the 220 volt (double)
breaker with a 120 volt (single) breaker, put the black wire on the breaker,
use the red as the neutral, (mark it with white tape to indicate this is
it's new purpose), and use the ground as the ground.

If you've never worked in a panel before - stop, call an electrician.

Best of luck.
Matt