This might be crazy, but i stopped breast feeding my son at 6 weeks, he is 4 mo. old. can i start again?

Unlikely: Production of milk is a feedback loop. You stopped when you child was 1 1/2 months old and now 2 1/2 months have gone by. The "factory" probably has shut down. By now your child has gotten comfortable with the terrific flow from a bottle and will be resistant to return even if that were possible. Carry on.

Start again: Yes no harm trying yo breast feed again , hard , but it may work . Drink a lot of liquids and nurse every 2 - 3 hrs. All the best.