Depends on the item.
If it’s cotton then you’ll need a sewing kit equipped with thread and a rag,activate it and use it on said item,if it’s leather then do the same but with a leather patch,both can be obtained by cutting up clothing.
If it’s metal then you’ll need a soldering iron with battery in it,and scrap metal/metal chunks/metal whatever,if it’s plastic then you’ll need the same but with plastic,metal is obtained by smashing up lockers and metal cases and stuff,plastic is a little less common,I advise you check a bunch of bathrooms,find cough medicine,dump it out,and cut up the bottle which is plastic.
If it’s a gun then you’ll need a gun repair kit equipped with duct tape.
I don’t think anything can be done for wood however,so that’s your baseball bat trashed.