You probably need time to adjust. There's no instant fix that turns everything bright quickly. But it's worth realising that you once started a business and built it up, and there's no reason you couldn't do the same again; but next time you have more experience, more knowledge, so should find it easier than last time. It just seems not to be so at present. Remind yourself that, that feeling's not really the case.
Everything changes, and when life brings you down, then the next stage is going to be 'on the up'. Plus, think of those things you still have and which you value. They form your bedrock to rebuild your life and help you face life's challenges.
Take things a day at a time; any small advance gradually builds until you are in the swing of things once more, and winning once again. Just don't expect the transformation to take just a day. But it will come.