Hi Dev,
Very sorry to hear your data loss problems. It is very disheartening. I don't program games, but I have had similar programming data losses where I must rebuild from the previous version. It has happened more than once, even with good backups. Not trivial programs either, but thousands of lines in the control systems space, mostly in C or C++.
My only consolation is that whenever this happens, I find that the rebuild is much faster than the original build process. It is amazing what you remember from the first build and the mistakes you don't make the second time around. Also, I have found my code is better than the first build as the overview you get in reconstruction produces an overall better outcome. But this memory won't last forever.
My recommendation is that if you move to your other project you will forget the details which would have made the rebuild easier. As frustrating as it is, I think you should rebuild ToU while the knowledge is in your head.
Regards,