Is drinking a regular protein shake before bed going to help heal your muscle or will it convert into fat?

Depends --: If the person is in actual need for muscle repair and he/she is not overweight already, then it can be useful -- otherwise any excess calorie will be stored as fat in the body.

Depends: If you're malnourished, the protein shake could help. If you eat the number of calories your body requires, the protein shake will, indeed, be converted to fat.