No, muscles cannot turn into fat, and fat cannot turn into muscle. If you stop exercising, you will see a loss of fitness and strength. Half of the fitness gains you made will be lost in 1 to 3 months. The longer you trained, the longer it takes to lose the benefits.
What actually happens is:
When you stop exercising your metabolism slows down and you burn less calories. So unless you reduce your caloric intake you will likely see a fat gain and loss of muscle from the absence of exercise.
To avoid this, combine some form of strength training with healthy eating…LiveFIT!