I thik the OP is referring to the female threads and not the bolt.

OP, you could just drill and tap to the next available size of bolt.

 

yes sir. its the female thread. sorry i don't know what that part called. half of that encircled in the picture was the thing that broke up. im not sure if putting a bigger size of bolt will work, since there's no more thread that will hold on to the bolt. also, i am not sure of bringing it to machine shop and have it weld will also work, and will last long?

thanks for all the advise sir.

 

Loose threads, drill the hole removing whatever thread is left. Make new internal thread using a "tapping tool". Ask a shop, they know what to do.As for welding, i cant remember what type of metal is that part. Different metals requires different welding electrodes.