Can i get pregnant at 45 naturally.i have been trying for 3 years?

Yes but doubtful: Pregnancy chance each month depends on many factors but most important is the woman's age. Fertility declines with age and at age 45 is less then 3% each month with over 70% chance of miscarriage due to chromosomal abnormalities. Male factor and tubal or uterine factors could also be involved. I recommend donor egg recipient ivf or embryo donation at age 45.