That depends if it actually snapped, like broke, or just got bent real bad. If it actually snapped, depending on how far into the stalk the crack goes, it MAY be repairable. Try some gardener's tape around the crack, or even some masking tape. There are no guarantees it will survive though, depending on damage. If it merely bent,you should be able to prop it up with minimal worries. Get a stick or a straightened hanger and stick it in the soil and tie or tape it back up. Marijuana is an extremely resilient plant, they're actually somewhat hard to kill, so it should be OK if it's just bent bad.