its now touching the roof because of the head rest,
Just a couple of suggestions: first, now that the headrest is fully up, the support pillars must be exposed. so I would run some release fluid down the pillars into the seat holes, so that any catches or corrosion are eased and won't stick in place.
Second, it's unlikely that there is NO device to hold the headrest at its set height. If it's simply friction then the release fluid should help free things up. More likely it's some sort of pawl or barb, or a sprung collar that cuts into the support pillar from one side, and is freed by pressing in the opposite direction using some button or collar where the pillar enters the top of the seat.
I have seen these where to release, you have to - counter-intuitively - push the release button towards the pillar rather than pull away from it, but others you may have to squeeze together equally from both sides at the same time.
It's unusual, but there's always the possibility that the release button might not be in the seat or around the pillar, but in the headrest itself.
Don't overdo it with the release fluid as it could cause problems by swelling or otherwise adversely absorbing into any rubber or plastic components inside the seat back.