I need an advice(dmv related)

[Sideways_blksr20]

I
Bought a zenki from a guy here in zilvia . He didnt have the title , he gave me a bill of sale and the registration, the problem is that the car has bever been register on california i went to the dmv and they said thet cant do
Nothing about it , i contacted the dmv from colorado and they cant send me the title cause still under his name.. Now the guy wont answer my calls or txts .. How can i
Register this car ?
I have the bill of sale sign by him
Colorado registration
Colorado plates