a while back while i was doing the mission to restore power at helios one, i activated archimedes and destroyed all the ncr troops there.

now i'm doing restoring hope but there's no one at helios one, can i still go back to the ncr at camp mccarran?

i don't want restart the game (since i have all the dlcs and i've completed them).

If you are looking for the supplies you can find them in the wastes between Helios One and Camp Forlorn Hope.