I need to know about the feasibility of my dream project. I would like to make a software in which DNA of every person in this world is stored. So if any child is found somewhere, we could use his blood sample to find where his parents live. Thus we could even stop orphanages. Is it possible or does exists already?

Serious issues with data protection and privacy.
Also consider the vastness of your proposal and the data involved.
There are currently some 7 BILLION people on this planet, increasing at a rate of about 255 worldwide births per minute !!

I am curious. How does a DNA 'bank' stop orphanages? Knowing who and where the parents/relatives (if parents are not available, how wide does your search go?) are does not mean they would want the child. Are you going to force families to take in children just because the DNA matches?

And it would also be abused by governments and law enforcement officials in ways that violate an individuals presumption of innocence in many countries. And was pointed out, who is going to force compliance when there are cultures that are barely evolved beyond the stone age.

Certainly it's possible - it's just a large database, and we already have such databases for DNA samples from felons. I'm sure that most countries have such databases. So technically it's not unreasonable. But you're proposing that (a) everyone be forced to provide samples so that the database covers everyone, and (b) it would be global. Who do you suggest own and control access to the database -the United Nations? And what penalties do you propose for those of us who would refuse to comply?

Feasibility from what angle? From the database angle it is certainly feasible. As noted such databases already exist on a limited basis. Mostly they stroe DNA of felons who were required to submit as part of an arrest. From the practical angle forget it. There is no way you are going to get a sample of "every person in this world".

As noted there are issues of who would manae such a database and all the privacy concerns.

Finally, you goal for the database does not make sense. Not being able to reunite a child with its family is not the reason orphanages exist. Such a database would have an extremely limited, if any, effect on orphanages.

The main uses of DNA testing is 2 fold. One to establish paternity and two, to convict (or show the innocence) of those accused of a crime, by using DNA evidence to prove or exonerate.

I just want to add that there is more than one kind of DNA data. Ancestral DNA databases are growing daily, on a voluntary basis, but they don't identify individuals, only groups by where they lived and when. Identifying exact lineage is problematic because only the men in the family can be connected directly down through the family tree. It's more complicated than that, but that's the simple version.

@joy. Are you sure you are correct about only men in the family. I thought it was mitochondrial DNA (female) was the only traceable DNA for each family.

I misspoke - the two DNAs are separate and go back only through all men or all women.
Exact match DNA testing is just that. Going back further gets more vague unless you have lots of close family names all of whom have been tested, to get the 'group' going. As you go back, you are just getting ancestry based on where people migrated from and to, and certain markers for race and so on.

The maternal line is often much harder to go back very far because of name changes when married. You can't just get tested and expect to find matches to relatives. It's a lot of work, and you need to choose a site that has a huge database. I think the 2 biggest ones are ancestry.com and FamilyTreeDNA.com. The more people who join and get tested and enter the results online, the more other people can find connections. But I've read a lot of the information from people looking, and the terminology alone is so strange that you have to really study it for quite a while just to get started.
The last time I looked into this was about 4 years ago. I have a feeling there's a lot more group data now. I know that over the years, new subgroup classifications get added all the time.

BUT again, this isn't for matching orphans with family. It just won't work.