Renal infarction kidney, how long is the recovery?

Depends : Hard to answer because it depends on the cause, how severe, and how much kidney was affected. Infarction means tissue death, so the amount of kidney infarcted is lost. If only a small area 20% of one kidney, there is not likely to be much harm. The more kidney affected, especially is due to a systemic diseases i.e. Massive shock and low blood pressure--it may be significant.