Would it be possible for someone to be sitting in the middle of a sofa, to shoot them self in the head with a 45, the bullet enter just in front of the temple, go at a downward angle through the head, exit the lower center of the scull and land in the ceiling perpendicular to the sofa just above the crown molding? His forehead landed on the coffee table in front of the sofa.
Thank you

Depends on how he is sitting on the sofa, with his head down near his knees perhaps, then a upward bullet would appear to have went downward though the skull but be actually going upward.

Is it possible for the bullet to have landed in the ceiling perpendicular to the sofa? I would think that it would have landed in the ceiling behind the sofa.

Also, the coffee table was in front of the sofa, so wouldn't his head have had to be on the table or very close to it? Thank you for your response. I am just trying to make since of everything.

Have you considered ricochet? The projectile bouncing off any object (or even more than one object) it can't penetrate can make just about any final location possible.
Also, as chuck said, the position of the head at the time of the shot being fired is impossible to predict.
Is foul play suspected? Any evidence to support that it wasn't suicide? More is needed than just the final position of the bullet.

'sitting in the middle of a sofa' says basically nothing about how he was sitting
'go at a downward angle through the head' is anything within a 90 degree range downward and also isn't much help
'exit the lower center of the scull' is almost completely meaningless unless you say exactly where on the skull (a scull is a kind of thin boat)
'land in the ceiling perpendicular to the sofa' is meaningless too, given that a ceiling is parallel to a sofa, not perpendicular

If his forehead fell off, that suggests that the bullet went through the top of the frontal lobe rather than downward from the temple, so I agree with those who suggest ricochet.
This is just too complicated and poorly described for you to get a reasonable answer.

Wouldn't a ceiling be parallel to a sofa?

That's what I just said too.

I think this person just means 'straight up to the ceiling near the molding.' So the trajectory is perpendicular to the sofa. (Not meaningful.)

Bullets, even slow and heavy ones like the .45 that you mention, can do strange things when going through something. But like others have said, from your description, it is pretty difficult to tell exactly how this all went.

I am certainly not an expert. Possibly to clear things up a little. His forehead did not fall off. His head landed on the coffee table forehead down. The bullet landed in the ceiling just above the crown molding from the wall perpendicular to the sofa. I do not know where the gun was, as we were told three different placements by three different cops. The police report does not state where it was. I was told there was no gsr test done. Also, there was no evidence of the bullet hitting anything else.
Please, I am not trying to be problematic. I know nothing really about guns. I just need things to make since.

The medical examiner will have better answers for you as they will know what angle the bullet entered and exited the body.

I hope you find the answers that you are looking for. Good luck.