Drop back down immediately. Take a deep breath and review the hands you played. Did you lose to bad play, to better players, or because of bad luck?
You may be tempted to play one more session to see if you can win back your losses but this would be a mistake.
Protect your bankroll by moving down to 5NL immediately. The majority of players who shot take fail at the first attempt. The trick is not to get tempted and decide to see if you can win your losses back. This is how inexperienced poker players go busto.
Regroup, study the hands you played, and grind 5NL until you are rolled again for another 5 buy in shot at 10NL.
Rinse and repeat until you hit the ground running at 10NL.