1.Can functionality of bladder return after inability to empty bladder completely? 2.Does clamping Foley help to retrain bladder?

Possibly. . Whether bladder function can improve or not depends on the reason for the loss of function, the severity, and duration. See your urologist or a specialist in voiding dysfunction. The strategies that tend to work best involve clean intermittent catheterization, where your progress in emptying the bladder can be tracked. But ultimately, the plan should be developed based on your clinical situation.