My son (aged 4) has begun to sleep in his own bed, in his own room. But, almost every night, he wakes up saying he had a bad dream. What do I do to tackle this problem?

As this is still a transition for him, maybe you can try sleeping with him in his room for the time being. However, you need to let him know that this is only temporary. After he seems to be more settled, you can stay in his room till he falls asleep and then return to your own room. Hope it works. :)

Make sure your child has a sleep routine that helps them slow down, and feel safe as they drift off to sleep. This might include a bath, reading, or some quiet talk about the pleasant events of the day. Avoid scary movies, TV shows, and stories before bed.

my son started to sleep alone in his room my mom advise me to decorate the room the way he will lik in the way it encourage him also teach him to pray jdt before he sleep it daz help

Try reading him a happy story before he goes to sleep. Or telling him to remember a happy memory.

thanks