V4 has had two versions.   In the original, she was nude and bald.   In the Vicky 4.1 edition, she loads wearing a fuzzy bikini and has an anti-typhus hairdo.   I don't think that installing V4.1 can rescue your file (assuming that it was created with basic V4), although...

...V4.1 needs the folders called "DAZ People" in the main Poser directory path, i.e. not in an external runtime.   If you installed V4 into the main Poser runtime, so that you can replace V4 with V4.1 in the same directory path, I suppose that you just may have a chance to re-open the file that way.   If you are lucky and one or other saved file opens, immediately follow what pjz99 said.

Otherwise, you need to play tricks to save memory, I suspect.   Close anything that doesn't need to be running, before trying to open your file.   Once Poser is open, minimise it and then maximise it again, before attempting to open the file.   You may find that a reasonable amount of memory is freed by these gimmicks.   Again, if ever you get the saved file opened this way, refer to the instructions from pjz99.