In many situations, the character is simply stuck online and the error will resolve itself. If your character was disconnected, wait 15 minutes before signing back in. In the meanwhile, you can play with other characters. Try login back into the stuck character after 15 minutes have elapsed. Please try the following if it doesn’t work:
Use “Emergency Escape” to get out of a situation where your character is stuck and unable to move.
Menu (Esc) > Option (F)
After selecting [Emergency Escape], press [OK].
You will be moved to the nearest [Soul Pyre] activated.