Take a look at this chart, the Circle of Fifths: https://en.m.wikipedia.org/wiki/File:Circle_of_fifths_deluxe_4.svg

5 sharps is B major, which is the same notes as if there were 7 flats/C flat major. So even though 5 sharps would be the same notes as C flat, it wouldn’t be as accurate to call it that (instead of B major), because C flat would have 7 flats.

I’ll give this a shot

> if I have 5 sharp notes c#, d#, f#, g#, a#

so far you’re in B-major, but your sharps are out of order (should be f#, c#, g#, d#, a#)

> which is also called flat notes

false. Sharps and flats are different.

> So how can i find is it in b-major or c# or d flat major

For starters, you’ll only be in a “flat” key if there are flats in the key signature; you can eliminate d flat major already. Second, you would distinguish between B and C#-major based on how many sharps there are. B-major has 5 sharps, C#-major has 7 sharps.

> In the kye signature I have 5 sharps then it is B major kye

Yes

> if it have 5 flats it is in c# major kye

No. A key signature of flats is not in a “sharp” key. 5 flats is D-flat Major.

> my confusion is both kye have the same black notes I don’t matter if we call it sharp or flat the notes are the same

You are creating your own confusion, here. It does matter what you call them. It is true that C# and D-flat use the same black piano key, and it is true that they will sound the same because they are the same pitch, but they are not the same note.

To put it frankly, you have to make it matter. C# and D-flat might sound the same and are performed the same way physically, but they aren’t the same. Saying they’re the same, or saying that it doesn’t matter, is doing you a disservice, and that’s why you’re confused. The rules of music dictate that there are certain intervals between every note of every key, and if you start mixing up sharps and flats in the same key, you break the rules.

> if there is a difference then what is it

They have different names and they have different functions. A sharp raises a note and a flat lowers a note. I would look at a chromatic scale (sheet music) while playing each note one at a time. Start with C. The next note HIGHER (right on the piano) in the chromatic scale is C#. Then D, then D#, and all the way up. When you get to the top, that’s the note; let’s say it’s a “high” B, and now we’re going in the other direction. But then on the way down (left on the piano), you are lowering notes now, so the next note down is going to be B-flat. Yeah, you’ll play it the way you’d play A#, and it sounds the same, but you’re not raising the A, you’re lowering the B, so you have to call it B-flat. I suspect doing this will help distinguish between sharps and flats SOME. You’ll have to do some of the mental work, though; it’s not just going to make sense - you have to think about it.

> how can I find the key if I have five black notes

Well, you have to distinguish between sharps and flats, first. But each number has a certain key. Check out something called The Circle of Fifths. It’s got all the info you need, but it’s way too complicated to explain in a Reddit comment. Read that page, it will help a lot.

But also stop calling flats and sharps the same thing. They are not.

While it is possible to construct the rules around the notes of a scale that belong in a key, the key itself really makes sense when paired with music. It is the music that determines the key signature that would be "correct".

One way is to play the music and see how the melody resolves to a "home" note. That would usually be the "correct" key signature.

The other way is to let the composer decide how they intended their composition to be interpreted.

At the end of the day, this is "music theory" not "key theory" or "note theory". So let the music guide you.

EDIT: Once you figure out the tonal center of the song, then the notes to use for the scale must have (and this is always true) ALL the notes "A, B, C ... G" in some sequence which tells you whether to use the flat or the sharp. For example, you should not get B, Dflat, Eflat... because you skipped C. It would be B, Csharp, Dsharp.