Treatment depends on the reason for the block. It can be from a stone, enlarged prostate, stricture(narrowing) of the urethra, and many other reasons.

Blocked kidney is an emergency. It needs immediate resolution through the help of urologist or Radiologist. You need to seek immediate help from a urologist who will advise on next step (either urologic procedure, or nephrostomy which means the radiologist will put a tube from your side to the kidney to drain urine to the side in a bag until the urologist figures out how to fix the problem and what is causing it).

What has blocked your kidneys? See the urologist.