Sorry to heat that. It's hard to face losing all photos of children. The only solution is trying to get them back, as they won't come back by themselves.
You can either ask help from data recovery expert or try free hard drive recovery software. That depends on your budget. Therre are quite a lot recovery centers and tools (I googled such problem just now), but I don't know which one is the best. You have to make the decision on your own.
So much I can help you, as I have little photo recovery experience, the only tool I've tried is eassos recovery, but I have no idea whether it is the one you are looking for.
Good luck
Have a nice day
