Clogged milk ducts

Hi Mummies! My LO is approximately 6 months old, and i do have lots of milk, pumping 4 hourly in the day and none at night. Last pump at 930pm and the first pump at 530 am every morning. However, my milk ducts were blocked since last evening. Any remedies and how many days does it take for it to 'recover'? Thank you in advance!