#1
just changed strings and now im getting a buzzing sound from about the 8th fret on, I tried to fix it from the bridge but it didnt work what should I do?
#2
Keep playing it awhile, strings always buzz when you first put them on.
Gear

Custom fender stratocaster
Tokai Love Rock
Gibson ES-335
Vintage Ibanez V
Dillion PRS style

Fender DeVille 4X10
Peavey bravo 112

Ibanez TS-9
Ibanez DCL
Marshall Govnor 2
Little big muff
Boss ds-1
Boss me-50
Crybaby wah
#4
you may have used strings with a different guage as the kind your guitar is built for.
try to remember what guage your strings where before the change.
it it was a strat style guitar it was probably set for .10s
if it has a floating bridge its set for .9s