Acute kidney failure need rapid medical attention. The good news is that acute renal failure is frequently reversible. After the underlying problem has been addressed, the kidneys normally begin functioning again within a few weeks to months. In some cases, the damaged tissue may be replaced by scar tissue which prevents any further loss of function. In general, the greater the damage, the more likely it is to be permanent. But even with severe damage, many people recover enough function to avoid long-term problems. The only way to know for sure whether or not you will regain kidney function is to check with your doctor and do more research online.