Is the end goal to just have an available outlet at this box along with the switch?
First thing would be to make sure you have 120VAC available at this box. The assumption is that tucked back neutral runs to the neutral bar in your breaker box, and that black is your hot wire, but for all we know perhaps red is hot and the neutral goes nowhere. So pull all the leads, turn the breaker back on and carefully check that first with a meter. If the switch operates a light, remove the bulb so you don't get a false reading (backfeed).
If you can't get 120VAC on the meter using the neutral wire as your common, try measuring again using the ground as your common (for test purposes only). In this way, you can at least identify which is hot..black or red.
If you determine neutral isn't connected, you'll have to figure out where the other end terminates and if you can pick up a good neutral connection there.