You have 2 options-
Option 1- Dont restart. Slowly make more money and your people will come back. The more money you put into the kingdoms treasury the more people come back/
Option 2- Restart the game. Buy houses and stores as you go along. Set the rent to high. Get to being King (or Queen) and STOP PLAYING. Wait around all day why your money comes in. Do side quests if you want. Get money, then spend it on more propeties. Amass at least 7.5 to 8.5 mil gold. You only need 6.5 to save all the people, but the other money is too fufill your promises.
It will take very long. I reccomend starting Thursday or Friday night, then finishing up on Satuday.
I did the 2nd option. I amassed my gold with no cheats. I was 100% good. I saved everyone.