VPN dont work after admin password change on Windows 2003 SBS

The adminpassword was lost on a Windows 2003 SBS machine. I resetted it with a tool from DVD, but now did the VPN not work. the same problem was the account on dyndns. I changed the account. I can see that the client ist connected but the programs (explorer an other) didnt show any data. The domain (says workgroup on the client ???) meens the client have not enough rights to open it. Who can help? What ist the problem ?