Can i sue a person who shingled my roof 16 months ago and it started to leak we had no contract?

You'll need to gather your proofs. Even with no contract, a canceled check, credit slip, or written estimate could be sufficient proof. The judge will expect that you made a doented attempt to have the roofer resolve this dispute with phone records and written attempts before filling. Small claims court fees are negligiable. Also most states have a two year limit on civil claims so don't let this lag much longer.