Helping a friend to pull down garage, I fell through roof and broke my leg.
I am self-employed and now have no income - (vacant land, only old stone garage on block)
Is there anything I can make a personal injury claim on?
As owner of the land, your friend would owe you a duty of care as occupier. In SA, an occupier only be found to be negligent to an entrant for an injury they suffer on their property if the occupier fails to take precautions against risks of harm that are foreseeable and not insignificant and in the circumstances a reasonable person in their position would have taken those precautions. (An occupier is not required to make their place of business or residence incident proof.) Then you will need to prove that your friend's negligence caused your injury.
All of this will depend very much on the circumstances of what led up to and what you were doing at the time of the incident. If for example you were doing something that was risky and you knew the risks involved, then you would not be entitled to compensation because you assumed the risks. However, if there was some glaringly dangerous risk which your friend knew about but failed to warn you about and that risk resulted in your injury then you may have a case.