You might need to be a bit more specific (I.E. will not crank, Cranks but will not fire up.) How did it run the last time you drove it? It will be much easier to help you if we had a little more information.
Get you a tuneup bro
Search Buick Roadmaster Questions
Are you a UK consumer? CarGurus now has a discussion forum in the UK.
Buick Roadmaster Experts