i changed the string of my steel string guitar(those selling in very cheap price.. )....
but thrs some unusual noise sounds like eeeeeee thing in the 4th string when i play it....
but this is not happening on the others.....(i change the strings myself)
wat is the cause of this and any way to solve the problem???

Did you change the string gauge? Or did you use back the old gauge???

I suspect it might be a string buzz lol, otherwise I'm not too sure what causes the noise.

bridge pin not inserted properly?
who knows unless got more info.

wats a string gauge???
and wats a bridge pin???

thx for the kindness...

String gauge is how thick your strings are.... make SURE you check what string gauge you put in before you change the strings.
If you don't know what your original string gauge is, I assume that it's the standard .12 gauge.....
The .12 is actually is in inches. Actually... it's .012.... So here are the most common string gauge (but there are so many variations for it), from thinnest to the thickest.

.012 .016 .024 .032 .044 .054

Don't forget..... this is for acoustics!!!! Electric guitars use different gauges.

So when you change your strings, make sure you know what gauge their are in.