*What kind of business can I start with zero investment?
Currently, there are many businesses that you can start without investment, so at the end of this answer, I will give you a list of jobs that you can do. The list is primarily for online jobs. If you desire to start a business either online or offline, you can begin at any time from anywhere. That said, everything depends on your skills and your passions. So, for example, I am going to talk about writing, assuming that you can write and develop it if you want to start it. Let me tell you how you can build your passion for it.
So now you decide on a topic that you have the command and good knowledge about it. Besides, choose to find out that the topic you will write about has a market and you can find the target customers for it. To start to write, do some more research and make a lot of notes about it before you start your writing session. Then ensure that you write at least 500 words daily; you do not have to worry about grammar and spelling. When you write like that, you will get into practice, develop a passion for it and stay in that; then, you become confident in your writing.
You will reach a stage where you have confidence in writing; now is the time to check your grammar and other things, so make it clean and tidy. Once you have done the needful, convert that into an eBook, approach some platforms, and upload your eBook. As you have done the first eBook, you would not like to stop it and will plan to continue from there to write more books.
Once you are happy with your eBooks writing, you will start to plan to make some real money that motivates you to convert your eBook into books and start publishing on famous platforms, and that leads to going into the publishing business. So, this is one example I have given you because this is what I do now. I have written 122 eBooks and books for the last seven years and hardly spent any money on this; therefore, this is one of my cost-effective businesses I can do from home.
In the same way, there are many other jobs that you can do from home without spending the money; say, if you are a good cook, you can start a food business from home and then take it to an outside location and expand it.