I have had a broken hand taken out of a cast and put in a splint how long till i can do heavy lifting again?

It depends: This is highly dependent on the type of fracture you had, location of the fracture and how long it had been in a cast. Most fractures are healed in 6-8 weeks, but the final decision should be made by the person most familiar with your particular situation.

3 weeks: Truly, this question can't really be answered here. It depends on exactly what your break was, how long it's been since the break happened, what does your x-ray look like, how does your hand feel... . Lots of factors! best to ask your doctor who put you in the cast.