Well first off let me state that the SOL has nothing to do with collection of the debt itself, they can continue to try to get their money forever. The SOL just gives a certain period of time where they can no longer take legal action by filing a valid suit against you to collect on the debt owed.
Even then, they can still file the suit, you would have to respond with the SOL as your defense to have the suit dismissed because the debt is time barred.
The SOL would start from the time the account first went into default, 30 days after the last charge or last payment was made on said debt. (If you have been out of state you can disregard all of this because the SOL stops counting while you are out of state!)
Now, that being said, the SOL in Virginia is 3 years for an open account, or 5 years if you had a written contract that you signed for the debt.
This is, of course, all only valid if they do not already have a judgment against you from a court suit.