You might want to wait about few minutes until reformat process is done, usually takes about 5 minutes, then you can try to re-login, if problem still occur, you can try to console your VPS using VNC, and see what happened inside your VPS.
You might want to wait about few minutes until reformat process is done, usually takes about 5 minutes, then you can try to re-login, if problem still occur, you can try to console your VPS using VNC, and see what happened inside your VPS.