Ok so somehow i messed up my guitar- and i know i'm gonna struggle to explain this. OK so when it tune the guitar, it'll all be in tune when unfretted, but when i play a new note, like F on the bass E string, it is completely out of tune.

How do i fix it???
Sounds to me like somebody messed with the saddles at the bridge. That's happened to me on bass before, and I know some guitars are setup similarly.

That's just my two cents; I could be wrong. I'll let a real guitarist take it from here.
The intonation is out.

Tune each open string to pitch, then see how the string fretted at the 12th fret matches. You then adjust the saddles at the bridge to bring them closer together. You'll need to retune each time you tweak the saddles.
THanks, was messing around like that trying to fix it, didn't know if i was doing it right though