My friend wants me to be her baby's dad. The baby's birth certificate doesn't have the biological father on it and wants nothing to do with the baby.
Can I go on the birth cert legaly please help with as much advice as can thanks

No, if you are not the baby's father, it would be fraud ( and you can be charged in criminal court for it)

You say "friend" so you are not a boyfriend? You are not living with her? You are willing to pay child support all of the next 18 to 21 years ?

The birth father wants nothing to do with the child so am I able to be put on birth cert or legaly adopt the child

the birth father wants nothing to do with the child so am i able to be put on birth cert or legaly adopt the child

Some states have restrictions. You must be married at least for a year to adopt the child.
Another question... as Chuck said signing a BC constitutes fraud, but I know no one has been prosecuted...
You are willing to pay child support all of the next 18 to 21 years ?

The bio father has little choice in this matter. If he did father the child he has to pay support if she goes after him.

If you want to be the father and assume all the responsibilities that entails, then you will have to adopt the child. This means following whatever laws are applicable. I would suggest that you consult a local attorney to find out what is necessary.