How do I switch my 4wd back to 2wd manually? (Broken shifter)

So heres the thing, from what i can tell the clip/bolt that holds the 4wd
linkage stuff in place broke off, so now the shifter moves freely, and Its stuck
in 4wd. What kind of bolt/clip do I need to replace the broken one that held it
in place, and also how do I switch it back to 2wd for the time being? Because
I still need to drive it in the meantime, and I would rather not hurt my truck by
driving it on dry pavement in 4wd