My six string E cannot be tightened. Mystring tightens to an extent which is very loose after reaching that extend, the peg keeps rotating but the string does not tighten. I am talking about the the low string E, i opened up the string and wrapped it up again, but after 2 or 3 turns, the knob turns but the shafts doesn't
It sounds like the tuning machine has malfunctioned. It may be possible to disassemble and repair it, but probably easier to replace it. You will need a wrench or socket of the correct size and a small screwdriver.
Be sure to purchase a new tuning machine with the correct handedness. If this is the usual layout with 3 tuners on each side, then you want a "Left" one for the low E.
Edit: There was a suggested edit from an anonymous user that a "Right" tuner is needed. Bear in mind that "low E" means the E string with the lowest sounding pitch, not the one closest to the ground. Left refers to the left hand of the observer when looking at the headstock from top side of the guitar, not from an anthropomorphic perspective imagining the headstock to be a face with its own left- and right- sides. (I was a little unsure of this and checked a few online references and sales outlets. The confirmation is the fact that an inline headstock has 6 Left tuners, whereas a reverse inline headstock has 6 Right tuners.)
Scant information means the question may well not get a helpful answer, but we need to know if the peg around which the string is wrapped is actually turning, and whether you do mean the low 6th E string, or are mixing it up with the high (thin) E.
To try to answer - the string may be slipping on the shaft. It may have far too many turns on it already. It may be that the knob itself isn't turning the gear, as it's slipping on its own shaft.
Far more information, please.