(Please help me)

Does a 7th or 13th major or minor scale exist?

Maybe you are thinking of a Dominant 7th scale? If that's the case, then yes. Just play your normal major scale, but flat the seventh.

No such thing as a "13th scale". I kind of think that would be a redundant idea. There are only seven notes in a scale, as per a major key.

I suppose to get a "Minor 7th Scale" you could just flat the 2nd. But what is the point? That would be the same as the relative Major Dominant 7th.

Rock on!

well a 7th scale would be a dimished scale... and the 13th=6th so that would be aeolian scale.

Negative EMB. You have a flat 3rd, 5th and 6th in a Diminished scale. The seventh doesn't change... For example, C Diminished would be: C, D, D#, F, F#, G#, (A) and B. Anyway, that is an eight note pattern if you choose to include the natural 6th. Unless you meant something else.

Rock on!

i think i meant the 7th note of key would be the diminished scale... but im not entirley sure now :)

Do you mean "the seventh degree"? That would be the Locrian scale. If you take C Major, the seventh mode would be B Locrian.

Locrian is also known as "half dimished". Also, the 5th degree in a major key is also the relative Major 7th. So in the key of C Major, the dominant 7th would be G Dominant 7th.

Rock on!