You could get an experienced astrologer to do a chart rectification. This would be done by comparing your natal chart, progressions and transit with the times of the most important events in your life, e.g. wedding, birth of children/younger siblings, major moves, major career events.
An easier method would be to simply read descriptions of Virgo ascendant and Libra ascendant and see which fits better for you. If any planets change houses, read those descriptions, too. You won't get an accurate degree and sometimes there might be confusion if two placements both seem to fit equally, but it works in a pinch.
