E60Japanese

Hello everyone
Im happy to be here.
I just bought my first BMW. A 2006 E60 Auto
I bought it from a guy who hasnt driven it much for the last year because of two reasons
He is broke and the transmission will only drive in 3rd
You can select drive but it is in 3rd the whole time
reverse, neutral work fine
I can also drive with no noise at all

There are a few other problems like it needs new brakes etc but now my interest is the transmission

Im mechanically minded so I will understand most of what people tell me to do or check

I can fit a used transmission for about $1,000 or try and repair it

so anyones help and advice would be appreciated
I look forward to hearing from you