Help please? how long are bone bruises supposed to last?

Location dependent: It really all depends on the location of bone in question. If it's a weight bearing area like the foot or ankle, then it may take 4-6 weeks to improve. If it's near a major tendon attachment, like the Achilles, then it can 6-8 weeks depending on the corresponding treatment. Use heat and ice contrasts to the area to reduce swelling and pain.

Personally i find: they can last about 2-6 weeks