The spring on the inside probably became unhooked, it will most likely need taken apart. Its like 4 or 5 bolts that will need taken out with an 8mm socket and rachet with an extension, and then the recoil comes off. You can rebuild it in your house if you have to, all you'll need for tools is a screwdriver or something to remove a clip, and maybe a pair of pliers and maybe a knife.
Also if you've never been inside a recoil before Howdy has a great thread on rebuilding them if you search for it. Knowing how to fix a recoil is a great skill to have with these old trikes.
current rides:
05' 400ex
02' yz85
84' 200es big red
84' 200s with tlr200 engine project (almost done)
84' atc 110
83' 225dx with 340cc kohler sled engine